Future Cessna? Re-imagining the 172’s Interior Space

Future Cessna? Re-imagining the 172’s Interior Space

After months of research, a postgraduate student at the ArtCenter College of Design envisions the Cessna 172’s instrument panel and interior for the future.

We are pleased to present Baoqi Xiao’s concept for a redesign of the Cessna 172. 

Keep in mind that this is not a Cessna or Textron Aviation project. The design has not been subjected to the rigors of the engineering process or had to undergo the FAA approval process, so the designer was able to start with a clean sheet and dream big. After all, innovation starts with someone asking “What if...?”   —Ed.


As an open-minded design student, I am eager to have the opportunity to design all kinds of different objects that move across land, sail at sea and fly in the sky. Having focused on superyacht design for almost three years, I decided to explore new design territory by redesigning the Cessna 172 Skyhawk’s interior. (A superyacht, also called a mega yacht, is a privately-owned yacht more than 79 feet in length that carries a professional crew. —Ed.)

This project opportunity made me quite excited: I’m an airplane lover and have dreamed of becoming an airline pilot since I was a middle-school kid. From the Cessna 172 to a Boeing 747-400, I’ve learned to fly them all in a computer-based simulator. Even though I’m not planning to become an airline pilot, it is still fun to learn all those complicated procedures and fly jumbo jets in a virtual world. 

Although it’s been 12 years since the first time I touched a flight simulator, I still remember the day I was sitting in front of the computer, looking at tutorials online and learning basic flying skills on the Cessna 172. The 172 is an aircraft that brings all kinds of people into the world of flight, and is such an important and popular airplane for beginners. 

With all kinds of new technology changes coming into aircraft cockpits, how will flying an aircraft be different in the future? How will the Cessna 172 continuously adapt to the future of flying and to the future of flight training? It is time to think about the future of the Cessna 172. 


A brief history of the 172

The Cessna 172 is the most successful aircraft in history in terms of the length of its production period and the number of aircraft produced. Cessna has been focusing on producing this aircraft since the early 20th century. 

Nowadays, the entry-level airplane market is becoming more and more competitive. Other manufacturers such as Cirrus, Piper and Diamond are increasing the quality of their entry-level aircraft at reasonable prices. 

Even though the majority of Cessna 172 sales are to the entry-level market such as flight schools, and there are still a large number of these aircraft in service, the unique, legendary 172 might be starting to lose its luster. In order to remain a leader in the competitive entry-level market, I believe the Cessna 172’s design needs to be updated. 


The research process

During the early stage of this project, I prepared by doing considerable research on 172s. The process started by gaining an understanding of the Cessna brand and Textron Aviation’s current Cessna product lineup. 

I also identified the unique features of the 172 and performed a competitor comparison. I went to online forums to look at how pilots talked about the 172 aircraft. Researching the aircraft’s cockpit design trends was also on my must-do list. 

After my initial research, I was able to identify areas for more in-depth, in-person primary research. These focal points included the current instrument panel design, design of the seat, the luggage area and flight item storage around the cockpit. 

The primary research phase is really about getting out of the design studio and observing—in my case, getting hands-on time with real Cessna airplanes. Since I also wanted to see a pilot flying the airplane, I needed to find a way to take a flight in the Cessna 172. 


Flight school

In order to directly experience flight on the Cessna 172, I went to Pacific Air Flight School in Los Angeles for a one-hour demo flight. 

According to the flight school, I would have the opportunity to do the taxi, ground runup, takeoff and maybe even a landing. The one-hour demo flight covers every flight procedure, from preflight checks to tiedown at the end of the flight. I would fly to Catalina Island, then return to Long Beach.

For me, the previous experience I had with a flight simulator really helped a lot. Prior to the demo flight, I read the 172’s flight manual and studied the standard flight procedures. During the flight, I had a pretty easy time following my flight instructor’s directions. 

The first big moment came when I pulled the yoke back slightly as our airspeed approached 60 knots on the takeoff roll. The 172 gently lifted off from the runway. Though this was the first time I’d flown the Cessna 172, I could totally feel that this is was an easy-flying airplane. It’s very stable. When I needed to keep the 172 flying at a specific cruising altitude and on a specific heading, I didn’t need to apply much pressure on the yoke.

I actually got a pretty good feel for controlling the airplane during maneuvers. Based on my flight performance, my instructor Langston agreed to let me perform a visual approach and landing at the end of the flight. 

I was told to fly part of the traffic pattern visually. The first step was to visually line up with Interstate 405, which is parallel to the landing runway. After I did so, I was told to start turning and lining up with the runway. 

During these final turns, I identified a weakness of this high-wing airplane: the wing creates a big blind spot and blocks the pilot’s visual contact with the runway. 

Another inconvenience is the flap handle. It is too small and was too far away to reach when I was busy watching airspeed, altitude and trying to line up with the runway. 

This airplane can fly very slowly during final approach. It was easy to keep on the landing glidepath. 

After the flight, I also got the chance to interview the flight instructor about the airplane and get his insights about flight training.


Old versus new

My primary research objectives were to both understand the current airplane and to identify the design changes of the past few decades. These observations are important for analysis of the rationale behind the design changes. Therefore, the second phase of my primary research was to find an older Cessna airplane to look at, take a bunch of photos and compare them with the modern Cessna 172 SP which I’d just flown.

It took a while for me to find a 1960s-era 172. I found one at the Planes of Fame Air Museum in Chino, California. Their 58-year-old Cessna is still in good shape and serves as a commuter to bring museum staff back and forth between airshow locations and the museum. I identified several key design issues with the older aircraft. 

Keeping these items in mind, my next step was to talk to an owner to make sure everything I’d observed and noted was accurate and useful for generating a new design concept.

Interview with an owner

I was introduced to Sal Staiano through Cessna Flyer magazine. Sal is an experienced private pilot who owns a 1958 Cessna. He has hundreds of hours of flight time in Cessna airplanes and also has his multi-engine rating. 

Sal and I talked for about two hours. I received several insights that were valuable for designing a new Cessna 172 cockpit. 

We spoke about trends in cockpit design and Sal’s opinion is that the newer models of airplanes rely too much on digitalized instruments and automated function. Even though these automations are marketed to improve flight safety, Sal’s philosophy is that the most effective way to improve safety is for pilots to simply improve their flying skills. 

In my opinion, Sal makes some valuable points. With all these advanced functions, the airplane is definitely becoming easier and easier to fly, but technology can sometimes get in the way of just flying the airplane.

Assuming one of Cessna’s goals with the current 172 is to make the ultimate training aircraft for student pilots, the cockpit design for these airplanes should not be overly advanced and/or complicated. It should focus on giving pilots the chance to practice their skills in an effective way without too much distracting technology. In other words, the 172 should be an airplane that helps the pilot become a better pilot. Simplification may also help make the airplane more affordable as well. 

Speaking of technology, it’s important to consider the place of digital flight instruments and iPad navigation in a modern cockpit. Nowadays, many pilots use an iPad for flight planning and in-flight position reference. An iPad is unable to legally serve as a primary navigation source because it is not certified by the FAA. 

One of the biggest challenges with permanently-installed digital avionics is keeping the databases updated. The updates can be difficult to achieve, with sometimes many complicated steps, and it costs money, too. Pilots who are already flying with portable avionic devices know the pleasure of being able to quickly download an entire region’s worth of charts with just a simple tap. In the future, bringing an FAA-certified portable into the cockpit is a possible way to improve precision.

Instrument placement is another important factor in crafting a good cockpit. Cessna’s newer airplanes have made huge improvements in instrument placement when compared with the 1950s- and 1960s-era airplanes. The early 172’s “shotgun” instrument placement has progressed into a standard six-pack arrangement of primary instruments. 

The six-pack is well-organized and placed on the pilot’s side. The attitude indicator is in the top center of the six-pack with the other five instruments surrounding it for quick reference. This arrangement makes it easy for pilots to develop their instrument scan and cross-check skills for IFR flying. 

Some newer 172s are equipped with the G1000 digital avionics suite instead of the standard six-pack. The PFD of the G1000 glass cockpit is designed around the same principle of ease of reference. The attitude indicator has been enlarged and placed in the middle, with the horizon line spread through the whole display. Altitude, vertical speed, airspeed and heading data are placed around the side of the display. This upgrade increases scanning efficiency in the limited amount of space on the instrument panel. The G1000 glass cockpit also makes the entire cockpit look much cleaner—and the pilot can reach important information faster during multitasking.


Design analysis 

In keeping with the philosophy of helping pilots improve flying skills through a simple cockpit, the future Cessna airplane should have a logical and user-friendly arrangement of not only the essential flight instruments, but also the principal flight controls, trim wheel, flap switch, etc.

Among the many insights I gained from my research, one stood out as most important for the future Cessna 172: the focus on making the pilot a better pilot. My guiding principle for the next-generation Cessna 172 would be best summed up as “a well-designed basic airplane optimized for beginner pilots.”

To achieve this goal, it was necessary to classify and rearrange the information display into different levels. The information should be classified with consideration to how often it is used, how quickly it needs be accessed, and in what stage of the flight the pilot needs to access it. 

With this concept in mind, I intend to locate principal flight information on a single primary flight display (PFD). This info includes airspeed, heading, vertical speed, altitude and airplane status. The PFD—along with fine-tuning controls, such as elevator trim, rudder trim, aileron trim and flap lever—must be in an eye-catching and easy-to-reach location. 

On my design proposal, these items are in the middle of the instrument panel, as shown in the drawing above/left. When practicing basic maneuvers, the pilot can just focus on this part of the cockpit. 

The second level of information and control should be arranged on the two FAA-certified portable devices. These two devices serve as individual control centers for both front-seat pilots, or for the pilot and non-pilot passenger. The wireless portable devices for secondary flight controls would feature a combination of touch screen and analog controls. Second-level information (e.g., lighting, navigation, autopilot, etc.) could be reached directly by analog switches and knobs on the device. 

The third-level information would be reached through the touch screen and menus. Things like charts, flight route setup, GPS and checklist(s) could be accessed through a touch screen menu. 

One benefit of utilizing wireless portable devices is the convenience of planning and data updating. The pilot would be able to take these devices with them when they leave the aircraft. They can do flight planning directly on the device and update the database in one continuous workflow.


Conclusion

This project is still in the early stages. I drafted the basic concept based on the research I’ve done in the past few months. In order to continue to refine the concept, I need to further investigate FAA regulations and, more importantly, the technical challenges involved in making a Cessna 172 instrument panel. I think an internship at Textron Aviation would be a perfect opportunity to learn all these things. 


Baoqi Xiao graduates in May 2018 with a Bachelor of Science in transportation design from the ArtCenter College of Design in Pasadena, California. This will be his second bachelor’s degree; his first was attained in China, where he majored in industrial design. Send questions or comments to .

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Pre- and Post-overhaul: Engine Removal & Installation

Pre- and Post-overhaul: Engine Removal & Installation

Wise owners (and mechanics) know that a successful overhaul starts with careful engine removal. The overhaul process isn’t finished until after the engine has been reinstalled and the break-in period completed. A&P Jacqueline Shipe walks you through best practices to ensure start-to-finish success.

An engine overhaul is a daunting repair that usually takes several weeks to complete. In addition to the engine overhaul itself, there are several maintenance tasks that are associated with pulling the engine and reinstalling it after the overhaul. (For more about what comprises an engine overhaul, see “A Step-by-Step Guide to Overhauls” in the February 2018 issue. —Ed.)


Engine removal location and airframe storage

Once the decision to overhaul the engine has been made, the next step for an owner is to decide on the location for the engine removal. Some owners have their mechanic pull the engine and ship it to an overhaul facility. Other owners fly the airplane to the overhaul location and let the overhaul specialists remove, overhaul and reinstall the engine. 

The next task is to find out where the airplane will be stored while the engine is off the airframe. Hangar space is typically at a premium for both overhaul shops and general maintenance shops. 

Some shops place the airplane outside for the duration of time that the engine is off the airframe. The airframe is unbalanced and hard to secure on a tiedown once the engine has been removed. It is also much lighter than normal, leaving the aircraft more vulnerable to windy weather. 

Make sure to have a clear understanding with whomever is doing the engine removal and installation about where the airplane will be stored while the overhaul is taking place. 


Engine removal

Removing an engine from the airplane is typically not that time-consuming. The engine can be pulled easily enough in most cases in less than a day. 

Once the cowling and propeller are removed, the next step should be to take lots of pictures from all different angles of every section of the engine. This will help to determine the routing of hoses and control cables later on during the reinstallation process. 

The exact location of clamps is not usually specified by the maintenance manual and is left up to the mechanic. Knowing where the old clamps and supports were located helps ensure that everything fits properly during reinstallation.

Once all the engine components are disconnected from the airframe, the engine is stripped of everything that is not sent with the engine for the overhaul. The exhaust system, alternator, starter, vacuum pump and engine baffling typically don’t get sent in with the engine for overhaul. These components are either replaced or refurbished as needed by specialty shops. 

After all the necessary items are removed or disconnected from the engine, the engine itself is removed from the airframe. The tail of the airplane should be secured on a support that will hold it up once the heavy engine is removed. Most engines have permanent lifting eyes installed on one or more of the upper crankcase bolts. If an engine doesn’t have a lifting eye, one will have to be temporarily installed. 

A chain is most often used to attach an engine hoist to the lifting eye. Once the chain is secured, the engine hoist is raised until the chain has all the slack removed from it. Then, the bolts that secure the engine to the mount are removed from the vibration isolators and the engine can be lifted out of its mount. 

Once removed, the engine is either wheeled into the overhaul shop for disassembly or prepared for shipping if the overhaul is to take place elsewhere.

Engines that are shipped out by means of a freight company are generally bolted to a shipping pallet with a prefabricated mount. 

Owners that are having their engines sent out can save money by taking it themselves to the overhaul shop. The engine is often placed on a layer of used tires in the back of a truck and secured to four different tiedowns to keep it from shifting. 

In addition to saving money, the owner can have peace of mind knowing that he or she has overseen the engine shipment the entire time. Careless handling can damage expensive engine components and shipping companies do occasionally drop or damage items. 

If the overhaul facility is located a long distance from the aircraft location, shipping with a freight company may be the only option. In those cases, the shipment should be insured for the full replacement value of the engine. 

After the engine overhaul is underway, attention can be shifted to the repair or refurbishment of all the parts that are now easily accessible with the engine removed. 


Engine mount

Once the engine has been removed, the engine mount is easily accessible and can be thoroughly inspected for cracks and pitted areas. 

Even if the mount itself is in good shape, remove the mount from the airframe and inspect all the attachment areas on the airframe and mount for corrosion. 

Mounts that are free of corrosion and have good paint are often reused as-is. Mounts that are in need of repainting should be cleaned, lightly sanded and painted with a high-quality primer and then a coat of paint. 

In addition, any corroded areas on the airframe should be cleaned and treated or repaired as needed. 

Engine mounts that have pitted areas, excessive corrosion or cracks are usually sent to specialized welding shops like Acorn Welding or Kosola (now Aerospace Welding) for repair. These shops have special jigs and can cut out bad sections of tubing and weld in reinforced sections without distorting the shape of the mount. 

The firewall of the airframe is easily accessible with the engine and the mount removed. Now is an ideal time to clean and paint the firewall. Painting areas such as the firewall and the inside of the cowling with a bright color (usually white) helps to spot leaks easier. It also makes the airplane look better, and adds another layer of protection against corrosion.

Propellers

Controllable-pitch propellers and propeller governors are often overhauled at the same time as the engine. This ensures that the engine will be able to develop its maximum power within the proper limits without being held back by a sluggish or malfunctioning propeller or governor. 


Baffling

Metal engine baffles should be repaired as needed, and any worn baffle seals should be replaced to maximize engine cooling. 

Effective engine cooling is particularly important for overhauled engines because the new cylinder rings have to wear in and seat themselves against the cylinder walls during the first few engine runs. The extra friction will generate more heat than normal, especially in the cylinder heads. 

The air that the cylinders need for cooling should flow in through the front of the cowling, through the cylinder cooling fins, then down and out the bottom of the cowling. Any air leaks in the engine compartment that aren’t sealed off will allow cooling air to escape through a gap or hole instead of being ducted through the fins where it is most needed. 


Exhaust system

Exhaust system components are sent out for repair or are replaced if they are corroded, cracked or deformed in any way. Excessively thin or leaking pipes will only cause trouble later on. Leaking exhaust gases from warped exhaust flanges at the cylinder head connection will corrode and ruin the cylinder heads over time. 

Some overhaul facilities recommend replacing the exhaust system whenever the engine is overhauled. Turbochargers and wastegate assemblies should always be sent out for overhaul or replaced whenever the engine is overhauled. 


Hoses

All fluid-carrying hoses connected to the engine should be replaced at overhaul. Hoses become hardened and brittle after being heated and cooled during engine operation. A ruptured hose can cause a fire hazard or starve internal engine components of precious oil pressure. 

Also, tiny amounts of metal and debris can remain in old hoses even after they are rinsed and blown out and can contaminate the new engine. Many engine overhaul facilities will deem the engine warranty null and void if the fluid-carrying hoses aren’t replaced. 

It is also good idea to replace the SCAT hoses, but they aren’t critical like the fluid-carrying hoses are.


Oil coolers

Oil coolers should be replaced with new units or sent to an oil cooler specialty shop that can thoroughly clean the oil passageways. The oil passageways through the cooler have 180-degree turns in them that cause contaminants to precipitate out of the oil flow and build up in the turn areas.

It is impossible to get all the sludge, metal particles and dirt out of the old cooler by rinsing it in a parts cleaning vat. It’s not worth risking contaminating a freshly-overhauled engine with debris from the old engine in order to save a few dollars on the oil cooler. Clean oil coolers also have better oil flow through them and cool the oil more efficiently. 


Rubber vibration isolators

Most engines are mounted with the four attachments for securing the engine to the mount located on the rear of the engine. The rubber vibration isolators (often called “rubber engine mounts”) that are installed between the engine mounting pads and the engine mount should always be replaced whenever the engine is removed.

Vibration isolators lose elasticity over time and will begin to sag under the weight of the engine. Once the isolators start to age, they allow the front of the engine and the propeller to not only sag, but also to tilt down. 

The cowling is secured to the airframe and the propeller is connected directly to the engine, so as the engine mount isolators droop, the clearance between the bottom of the spinner bulkhead and the cowling becomes smaller while the gap between the top of the spinner bulkhead and the top cowling gets larger.

Isolators that are severely aged and distorted on these types of engine mounts can cause the engine to droop so much that the bottom of the spinner bulkhead actually starts rubbing on the lower engine cowling. 

In addition, rubber engine mounts are easily damaged and prematurely age if they are exposed to leaking oil or hot exhaust leaks. Constant oil leaks soften the rubber, causing it to swell and bulge. Exhaust leaks overheat the rubber, making it brittle and prone to cracking.

The isolators play a critical role in helping to secure the engine to the engine mount. They are typically not that expensive in comparison to other parts, and are easily accessible any time the engine is removed from the airframe—but difficult or impossible to replace without pulling the engine. 


Engine installation

The engine installation process takes longer to complete and is much more detailed than the engine removal process. Installing the engine mount on the airframe and then hanging the engine on the mount can be done quickly in most cases because there are usually only four bolts and nuts that secure the engine mount to the airframe, and an additional four bolts and nuts that secure the engine to the mount. 

Sometimes it is difficult to get the engine hoist adjusted just right so that the engine lines up correctly when attaching it to the mount. It can take a few attempts to get the bolts inserted through the mount and isolators. Components like the magnetos, fuel servo or carburetor may have to be removed to provide enough clearance to get the engine into the proper position on the mount. 

Engine mount bolts should always be torqued to the specified setting listed in the airframe maintenance manual and any specified torque sequence should be adhered to.

Once the engine has been hung, the baffling, accessories, hoses, oil coolers and all remaining parts can be installed. Clamping and securing hoses, wires and ignition leads is one of the most time-consuming tasks in this phase of the project. 

The exhaust system and propeller are usually two of the last items that are installed because once they are installed, they block access to other parts of the engine. 

Many overhaul shops run an engine on a test cell for an hour or so before sending the engine out. Some shops send the engine out with no run time on it at all. 

After reinstallation on the airplane, the engine should be started and run on the ground for the minimum time needed to ensure that there are no leaks; that the magnetos have the proper rpm drop when checked; and, if a controllable-pitch propeller is installed, that the propeller changes pitch as it should. 

Idle mixture and idle speeds should be checked and adjusted if necessary—but ground runs should be kept to a minimum, especially if the engine has not been on a test cell. 

After an overhaul, the rings are not seated. In order for the rings to seat properly, they must be blown out against the cylinder walls. The rings need high manifold pressures to force them to have metal-to-metal contact with the cylinder walls so they seat properly. 

Running an overhauled engine at too low of a throttle setting for any length of time (on the ground or in the air) increases the likelihood of glazing the cylinder walls. Glazing results from the oil oxidizing on the cylinder walls and creating a hardened surface that prevents the rings from ever seating properly. 

After the first flight, the cowling should be completely removed and the entire engine looked over for leaks and to make sure nothing has vibrated loose. Some shops will change the oil at this time if the test flight was the first run on the engine. 

The recommended break-in oil is generally used for the first 50 hours. After the 50-hour mark, there should be no metal in the oil filter when it is inspected. Metal found in the oil filter after this time may be indicative of an internal problem with the engine. 

Most overhauled engines perform well and provide many hours of trouble-free flight time and it is generally a relief for owners to have this major expense behind them.

 

 

Know your FAR/AIM and check with your mechanic before starting any work. Always get instruction from an A&P prior to attempting preventive maintenance tasks.

Jacqueline Shipe grew up in an aviation home; her dad was a flight instructor. She soloed at age 16 and went on to get her CFII and ATP certificate. Shipe also attended Kentucky Tech and obtained an airframe and powerplant license. She has worked as a mechanic for the airlines and on a variety of General Aviation planes. She’s also logged over 5,000 hours of flight instruction time. Send question or comments to .

  

Mentioned in the article

ENGINE MOUNT WELDING
Acorn Welding Ltd. – CFA supporter

acornwelding.com

 

Aerospace Welding Minneapolis, Inc.

awi-ami.com

 

To find resources for other components and services for engine overhauls, please go to the Cessna Flyer Yellow Pages at cessnaflyer.org/cessna-yellow-pages.html or contact Kent Dellenbusch at  or 626-844-0125.

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The “One-off” Cessna 620

The “One-off” Cessna 620

In its glory days, it seems Cessna never met a niche it didn’t want to fill. The company started post-World War II civilian production with the two-seat 140, then added the simplified 120, then came the four-seat 170, then the 180, the 310, the 172 and the 182. 

The Cessna 175—and later, the Hawk XP—were created to fill the narrow space between the 172 and 182. (The Hawk XP is featured in this issue of Cessna Flyer on Page 42. —Ed.) Faster and slower, retractable and fixed gear, pressurized and not, twin and single, conventional and tricycle gear, Cessna seemed determined to create an airplane for every mission and pilot profile. 

Given the multitude of models in Cessna’s lineup, it’s not entirely surprising that in 1956, Cessna sought to capture another market with the four-engine, pressurized Cessna 620. It was called the 620, because, you see, it was twice as much plane as the 310. 

Cessna management thought the time was right to introduce a plane that would provide more convenience for company executives than the airlines, but with more room and capability than the twin-engine aircraft of the day.

The 620 was introduced in 1956 and a single prototype was built. The aircraft was slated to sell for $375,000. 

However, timing is everything. Cessna was building a business-class piston aircraft just as the age of the business jet was taking hold. In 1957, Lockheed introduced the JetStar and in 1958, the North American Sabreliner was introduced. The highly successful Learjet 23 followed five years later. 

Despite Cessna’s heavy investment in promotion—including spending $25,000 to produce a film marketing the 620—the project was canceled. 

Don Powell, a Cessna employee who had been hired to recruit engineers for the 620 project, recalls the cancellation: “Every vestige of the 620 was to be abolished. Immediately. I had little plastic slide rules with ‘620’ on them, all kinds of gimmicks that I handed out in places... The story I got was that management was under heavy criticism by the stockholders for spending money on a model that had no chance of making money. So they took the plane, took out the engines and ran a bulldozer over the whole thing.”

Of course, Cessna would go on to produce its own line of business jets. The Cessna Citation families of aircraft comprise the largest business jet fleet in the world today.

Jennifer Dellenbusch is president of the Cessna Flyer Association. Send questions or comments to .

Sources: Wikipedia.com, “The Legend of Cessna,” by Jeffrey L. Rodegen, Write Stuff Syndicate, 2007.

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Cessna’s In-between Single – The R172K Hawk XP

Cessna’s In-between Single – The R172K Hawk XP

The final result of a three-decades-long quest to fill the gap between the 172 and 182, Cessna’s R172K Hawk XP is a stellar performer in a 172-sized package.

When it’s boiled down to basics, the Cessna Hawk XP (XP for Extra Performance) is a four-place Cessna 172 Skyhawk airframe, sporting a six-cylinder fuel-injected 195 hp Continental IO-360-K engine and a McCauley constant-speed prop. 

It’s a 172 on steroids. In exchange for over 30 percent more power, an XP pilot will also need to pay attention to three more items: the constant-speed prop, rudder trim and cowl flap controls.

Although the airframes of the 172 and 172XP are almost identical, Cessna certified the Hawk XP (R172K) under Type Certificate No. 3A17; a different Type Certificate than the 172. Other airplanes on the 3A17 certificate include the Cessna 175 and the 172RG. The R172 E, F, G, H and J on Type Certificate No. 3A17 were sold to the U. S. and foreign armed forces and were designated the T-41B, C and D models. 

Fill the gap

The Cessna Hawk XP was Cessna’s final iteration in its nearly 30-year-long quest to build an airplane to fill the gap between the 160 hp, four-door sedan-like Cessna 172 and the big-hauling, pickup truck-like 230 hp Cessna 182. 

1,454 Hawk XPs were built over a five-year period from 1977 to 1981. It’s considered one of the most successful of the gap airplanes.

The first iteration of the more powerful 172-like models was introduced in 1958 as the Cessna 175. The exterior of the 175 looks almost exactly like the 172, except for a distinctive hump in the upper cowling. The hump in the cowling was required to accommodate the propeller reduction gear housing. The 175 had the geared Continental GO-300 series engines which produced 175 hp at 3,200 engine rpm (but only 2,400 prop rpm). Serial numbers indicate that 2,118 Cessna 175s were built.

Army and Air Force 172s

In 1964, the U. S. Army bought a version of the Cessna 172 equipped with six-cylinder, 210 hp fuel-injected Continental IO-360-D and -DB engines as the T-41B and C. The Army purchased both fixed-pitch and constant-speed propeller aircraft, and later a 28-volt version (T-41D) developed for the U. S. Military Air Program. 

The Air Force ordered Cessna 172Fs in 1964 under the T-41A designation, and would eventually shift to the 210 hp IO-360-powered versions.

U. S. forces bought 518 T-41s. FAA TCDS listings indicate that the T-41s were produced from 1964 until 1981. 

Hawk XP production

Cessna airplane production and the number of active pilots soared in the 1970s to levels that had never been seen before and likely will never be seen again. In 1975, Cessna shipped more than 15,000 airplanes; the number topped 18,000 in 1978. That equates to nearly 50 airplanes a day, every day of the year. The number of active pilots peaked at over 825,000 in 1980. 

In 1977, just before the crest of this exhilarating ride, Cessna introduced the 195 hp Hawk XP, or to be precise, a modern derated version of the T-41D. 

By the late 1970s, Cessna’s 177 Cardinal and 177RG Cardinal RG production numbers had fallen. 1978 was the last year for these “nonstandard configuration” beauties; fewer than 100 units were produced. My supposition is that Cessna’s management concluded that the Hawk XP would be an easy-to-produce and reliable 200-ish hp replacement for the Cardinals.

Cessna gauged the market correctly. The Hawk XP was a hit. Buyers bought over 700 XPs the first year on the market. The following year, an additional 204 were shipped. 

Unfortunately for the XP, for Cessna and for all other General Aviation manufacturers, the bottom was beginning to fall out of the market. The decline in U.S. gross domestic product numbers tell the tale. GDP growth was at 5.3 percent in the third quarter of 1978; by the second quarter of 1980, the GDP number had belly-flopped to a negative 1.6 percent. The recession of 1980 settled in around the world. 

Hawk XP production numbers continued to drop; just 54 airplanes left the factory at the end of production in 1981.

Hawk XP features and faults

An Aviation Consumer side-by-side comparison of the 177 and the Hawk XP reported, “The XP was, objectively, inferior to the Cardinal. The Cardinal had better handling and visibility, much more cabin room, lower cabin noise, lower maintenance costs and virtually identical performance and load-carrying ability.” The article concluded that the six-cylinder Continental engine and constant-speed prop extracted a price in reliability, maintenance and economy. 

The Hawk XP’s fuel capacity is only 52 gallons, with 49 useable. The R172K pilot operating handbook cites a fuel burn of 10.2 gph while cruising at 6,000 feet msl and 72 percent power. This setting results in 124 ktas. The result—with a one-hour fuel reserve—is a still-air range of 471 miles in 3.8 hours flight time. 

Some references cite optional fuel tanks that increase the capacity an extra 14 gallons to 66 gallons, but I haven’t been able to find any printed data confirming this option. The 172RG, which Cessna produced from 1980 until 1985, did have a 66-gallon fuel capacity—and it’s on the same TCDS. I’ve heard of owners who have installed a set of 172RG wings on their Hawk XPs, but any other method of upping the capacity to 66 gallons seems to be impossible to find. (CFA supporter Flint Aero offers STC-approved tiptanks for the R172K. The tanks add 24 gallons of capacity; 23 gallons are usable. —Ed.)

All the Hawk XPs had a 2,550-pound mtow, which yielded a useful load with average equipment of around 950 pounds. 

The POH cites ground runs of 830 feet using “short field” techniques at 2,550 pounds and temperatures of 20 C (68 F) at sea level. The book numbers show it takes nine minutes to climb to 6,000 feet msl from sea level. Climb rate is cited at 860 fpm at sea level and 540 fpm at 6,000 feet msl. 

Another place the XP shined was as a floatplane. The TCDS provides for the installation of an 80-inch propeller—instead of the 76-inch one on the XP landplane—when floats are installed. 

Corrosion: an insidious blight 

Buyers and owners should know that Cessna only applied paint to the interior skins of its single-engine airplanes that were sold with a float kit. Therefore, always be aware of the strong possibility of airframe corrosion. One of the best and easiest ways to determine if airframe corrosion is an issue is to look at the skin surface above the headliner. 

Cessna Service Newsletter (SNL) 93-3 covers what I consider to be another must-inspect airframe item. SNL 93-3 cites the possibility of sometimes extensive corrosion that may be found under the lead-vinyl sound-deadening pads glued to the inside skins of the fuselage. The best place to start inspecting for this common problem is at the skin panels forward of the forward door post and below the windshield. 

Airframe ADs

While there are 22 airframe-specific ADs for the Hawk XP, most are easy to comply with. The most important is the latest seat rail and seat inspection and replacement information in AD 2011-10-09. Worn seat rails and worn parts in the seat rail mechanism on Cessna seats need to be in excellent condition to prevent seat slippage during flight. Seats that don’t lock securely are (often fatal) accidents waiting to happen.

AD 2001-23-03 calls for repetitive inspections of the fuel line and map light wiring and switch located in and behind the left forward upper door post for burning and evidence of fuel line chafing. 

A new AD will likely be issued in the near future which calls for the inspection of the left and right lower forward door post area of Hawk XP (and many other Cessna) airframes, especially where the wing strut and built-up door post join, for corrosion and cracks. 

Engine ADs

In mid-1978, and in all Hawk XPs beginning with Serial No. 2930 in 1979, the IO-360-K engine was replaced with an IO-360-KB engine. Both engines develop 195 hp at 2,600 rpm. 

The -K engine was certified in April 1976; the -KB in March 1978. Both engines featured oil-cooled pistons and counterweight-tuned crankshafts. 

Note 10 in the engine TCDS approves the installation of any engine with a B in the suffix in place of an engine without the B suffix.

The engine Type Certificate says that the -KB is similar to the -K except for a “modified crankshaft.” This seemingly minor difference is very important.

A clue to the crankshaft modification is contained in Continental Critical Service Bulletin (CSB) 96-8 in the following sentence: “In 1978 TCM began using VAR process steel in the forging of crankshafts for use in a number of its engines. The VAR process material produces a forging with fewer impurities providing the greatest reliability and resistance to unusual operating circumstances.” 

VAR is an acronym for Vacuum Arc Remelt. Earlier crankshafts were manufactured using a process called “Airmelt.” 

The Continental CSB was followed by AD 97-26-17 titled “To prevent crankshaft failure and subsequent engine failure.” The AD required replacement of all Airmelt crankshafts with VAR crankshafts whenever the engine case halves were split for any reason at all. 

The bulletin also says that any new Continental engines built after Jan. 1, 1981, are factory-equipped with VAR crankshafts. All Continental factory-rebuilt engines after Serial No. 210114-R for -K engines and 288506-R for -KB engines had VAR crankshafts installed by the factory. 

Today, Continental sells both -K and -KB engines, and both have VAR crankshafts. According to a Continental sales person, the TBO for a -K is 1,500 hours while the -KB has a TBO of 2,000 hours. The -KB TBO can be extended out to 2,200 hours if the engine is flown 40 hours a month, according to Continental Service Information Letter SIL 98-9. There is no additional upcharge from Continental when an engine with an Airmelt crankshaft is returned as a core. Factory new and rebuilt engines sell for around $40,000.

One thing to watch out for when shopping for a Hawk XP are airplanes that have flown little in recent years because the owner wants to sell without incurring the cost to buy a new VAR crankshaft. Remember, if the engine’s case is opened for any reason (not just in case of overhaul), the crankshaft must be replaced. Though Continental won’t upcharge to swap the crankshaft as a part of a factory overhaul, third-party shops will likely charge a hefty fee. 

Another crankshaft AD was issued as emergency AD 2000-8-51 in 2000. It was shortly thereafter superseded by AD 2000-23-21. Due to manufacturing defects that may have been introduced to crankshafts built between April 1, 1998, and March 31, 2000, certain engines defined by serial number must have a core plug removed from the crankshaft prop flange to determine if the correct metallurgy exists in the crankshaft forging. Further details are in TCM Mandatory Service Bulletin (MSB) 00-5C, dated Oct. 10, 2000. Modifications

One of the most significant FAA-approved modifications for the R172K ups the engine horsepower rating from 195 hp at 2,600 rpm to 210 hp at 2,800 rpm. This STC consists of replacing the colored arcs and redline on the tachometer, changing the internal stops in the propeller and modifying the prop governor settings. This mod is sometimes referred to as the Isham mod, after Brad Isham. The upgrade is sold by Plane Tools. The website claims that the mod results in “Near Cessna Skylane performance at a fraction of the cost.”

Other notable mods include the Sportsman STOL kit for improved STOL performance. The kit contains a drooped wing leading edge, aileron gap covers and replacement wingtips. It is available from Stene Aviation in Polson, Montana. Improved cowling fastener conversion kits are available from Skybolt and from MilSpec Products.

Dollars and sense

A search at Vref, the aircraft valuation company, showed an average retail price of $61,000 for a 1979 R172K Hawk XP with 4,650 airframe hours and 1,000 hours since overhaul. A 1981 version with 4,410 airframe hours was valued at $65,000. 

Add-ons, such as the Isham mod; a WAAS-compliant navigator such as a Garmin 530W; an engine monitor such as the JPI EDM 700; and an autopilot such as the Genesys (S-TEC) 30 with altitude hold would boost the price by another $15,000 to $20,000. 

The Barnstormers aviation classifieds website listed a 1979 XP with 692 airframe hours and the Isham engine modification for $149,000. A Canadian-registered XP with a set of floats and 5,600 airframe hours is priced at $135,000 Canadian or $109,900 USD.

For comparison, Vref figures for a 1979 Cessna 172N Skyhawk show a base value of $44,000. However, this lower valuation is offset by the average airframe time of 6,200 hours. The valuation for a 1979 Cessna 182Q Skylane shows a base valuation of $85,000 with 4,150 airframe hours. 

So, there it is. The Hawk XP fits just where Cessna intended it. It hauls more, goes faster and is more powerful than the 172 of the same year, and with the Isham engine modification STC it almost does what a 182 can do (but costs less). To top it off, it’s a good floatplane. 

Sources: Aviation Consumer Used Aircraft Guide (aviationconsumer.com/issues/1_1/); FAA TCDS No. 3A17, Rev. 46; Federal Reserve Bank of St. Louis (https://fred.stlouisfed.org/series/A191RO1Q156NBEA); Cessna175.org. Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and lives in Templeton, California with his wife Audrey. Send questions and comments to .

Resources

AIRWORTHINESS DIRECTIVES

AD 2011-10-09, seat rails

AD 2001-23-03, Repetitive inspection of fuel line and map light wiring and switch

AD 2000-23-21 (supersedes AD 2000-23-21), Manufacturing defect in crankshaft

AD 97-26-17 “To prevent crankshaft failure and subsequent engine failure.”

 

Proposed Cessna doorpost AD

The ADs and proposed AD referenced in this article are available under “Magazine Extras” in the Cessna Flyer forums at CessnaFlyer.org/forums.

 

For more Airworthiness Directives, 

visit CessnaFlyer.org and go to “Aviation Alerts” under the Knowledge Base menu. 

 

SERVICE BULLETINS Cessna Service Newsletter (SNL) 93-3

support.cessna.com

 

Continental Critical Service Bulletin (CSB) 96-8; Continental Service Information Letter SIL 98-9 and TCM Mandatory Service Bulletin (MSB) 00-5C

continentalmotors.aero/support/service-bulletins.aspx

 

MODIFICATIONS – CFA SUPPORTERS

Sportsman STOL kit Knots2U, Ltd.

knots2u.net/sportsman-stol-kit-cessna-170b-172-175/

 

Stene Aviation steneaviation.com/pages/sportsman-stol

 

Tiptanks

Flint Aero Inc.

flintaero.com/kits/internal-tip-tanks/165-2/

 

Additional Cessna R172K modifications & STCs cessnaflyer.org/cessna-yellow-pages/modifications-and-stc-s.html

 

MODIFICATIONS – OTHER

210 hp “Isham” STC Plane Tools planetools.com

 

Cowl fastener upgrades Skybolt skybolt.com

 

MilSpec Products milspecproducts.com

 

AIRCRAFT VALUE REFERENCE Barnstormers barnstormers.com

 

Vref vrefonline.com

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