Maintenance & Technical

Maintenance & Technical (120)

A&P Jacqueline Shipe lists dissects the system and offers troubleshooting tips for Cessna’s retractable singles. In the late 1940s and through the decade of the 1950s, General Aviation began to really take off as airplane sales increased. The postwar economy was favorable for the production and sale of both single- and twin-engine models, and the “big three” in the aviation industry were Beechcraft, Piper and Cessna. It was 1947 when the Beechcraft Bonanza appeared on the aviation market. The Bonanza was the first retractable single-engine plane on the market that had a wide appeal to a large number of customers. Sales were good, and in the late 1950s, Piper also entered the single-engine retractable gear market with the debut of the Piper Comanche. Cessna enters the RG market Cessna wasn’t going to be left out, and in 1959, the Cessna 210 made its debut. Early 210s were essentially Cessna 182 frames with a stronger engine and a retractable gear system that was very complicated in its design. The main landing gear doors had their own actuators in addition to the gear actuators, along with an accumulator for the main gear doors. The hydraulic pump on the earliest models was engine-driven.…
A&P Jacqueline Shipe describes how to service wheel bearings in this article, the second in a DIY series for pilots who wish to take on preventive maintenance of their aircraft. FAR 43 Appendix A lists the preventive maintenance items owners may legally perform on their planes. This list is fairly long—and some of the items are a little involved for a person to perform the first time by themselves, while other tasks on the list are pretty straightforward. There are several preventive maintenance tasks pertaining to the landing gear, including tire changes, strut servicing and servicing the wheel bearings. (Last month, Shipe discussed the steps involved in changing an aircraft tire. See the June 2016 issue for more information. —Ed.) A tapered roller bearing with pits on the rollers caused by corrosion due to water. Bearings: small but mighty While cleaning and greasing wheel bearings doesn’t seem like too difficult a task, there are some guidelines that need to be followed. The failure of a wheel bearing can cause major damage to the wheel and can even allow the wheel assembly to slide off the axle. Wheel bearings are relatively small, but are incredibly strong. They have to support the…
In the third article in a DIY series for pilots, A&P Jacqueline Shipe goes through the steps an owner can take in order to properly service the struts on their aircraft. Among the preventive maintenance items listed in FAR 43 Appendix A that pilots may legally perform on an airplane that they own is strut servicing. The struts on any airplane serve a critical purpose. They provide the shock absorption necessary to prevent the airframe structure from enduring too much stress from the impact loads incurred on landings. Even taxi operations impose stress on an airframe every time the gear hits a bump or uneven surface. The strut absorbs the bulk of these loads and prevents them from being transmitted to the airframe. Types of struts There are several different kinds of struts used for shock absorption. Over the years aircraft manufacturers have used different materials to limit the stress from the impact of landing. Some have used rubber biscuits, bungee cords and spring steel. The most common type found on most planes (and the only type used on fairly heavy planes from light twins all the way up to airliners) is the hydraulic air/oil cylinder, also referred to in…
Various things can cause nosegear shimmy. Here’s what to do. There’s nothing worse than completing a near-perfect landing and rollout only to have a sudden shimmy in the nosegear cause the whole front end of the airplane to vibrate. The shaking can be alarming to pilots who have never experienced it before, and can be worrisome for passengers. The vibration is also very hard on the airplane itself. A nosewheel shimmy is a rapid back-and-forth oscillation of the steerable part of the nosegear and wheel. It can be caused by a variety of problems, and it sometimes takes more than one trip to the shop to get the issue resolved. The nosegear has several points at which it pivots and rotates. These pivot points naturally wear over time, and excessive play in any one of them can cause the nose to shimmy. Cessna nosewheel design The nosewheel is turned left and right by means of a steering collar that is connected to the lower piston part of the strut through the torque links (i.e., scissors). The collar is connected to the rudder pedals via spring-loaded steering rods. As the pedals are pushed fore and aft, the collar is swiveled left…
Jacqueline Shipe, A&P, explains the technology and preventive maintenance for aviation batteries in her sixth DIY article targeted to owner-pilots. The bulk of the items listed in FAR 43 Appendix A, paragraph (c) that an owner may legally perform on his or her owned aircraft are primarily maintenance tasks that have to be performed on a fairly regular basis. This is definitely true concerning aircraft battery maintenance, and “servicing or replacement of aircraft batteries” is included on the list of 31 preventive maintenance items. All batteries begin to degrade in performance from the moment they are placed in service. The constant chemical reactions that take place cause an ever-increasing lack of efficiency within the battery. This is especially true of batteries that are allowed to run down and remain in a low or depleted state. Lead-acid batteries are the type used in almost all General Aviation planes and are becoming more common for turbines employed in low-cyclic applications like medevac. (Turbine powered planes in high-cyclic applications (i.e., airliners) often have nickel cadmium or “NiCad” batteries installed. These batteries are costly, and the servicing requirements are much more complex than for the lead-acid batteries. NiCad batteries should only be serviced by…
Finding and repairing a broken circuit is the subject of this fourth installment of A&P Jacqueline Shipe’s DIY series. Among the many preventive maintenance items listed in FAR 43 Appendix A that a pilot may legally perform on his or her plane is “troubleshooting and repairing a broken landing light circuit.” This specific entry is the only reference to electrical circuit troubleshooting on the list. Most electrical circuits for lights or pitot heat, etc. are fairly straightforward, while a wiring harness for a unit like a panel-mounted GPS can be very complex. This article will focus on the tools and expertise required to successfully troubleshoot a landing light. Study the diagram On any electrical circuit, the best troubleshooting tool is always the current wiring diagram pertinent to the model and serial number of the airplane. Learning how to read a wiring or system schematic can help a pilot not only in performing repairs, but also in understanding how a unit or system actually works. Everything electrical has to have a power source and a ground to operate. Some circuits contain numerous switches and circuitry that work in conjunction with each other to provide the needed power or ground. When a…
A look inside your aircraft’s vacuum system. When the earliest airplane gyroscopic instruments were introduced, the only available source for air pressure to spin them was an outside-mounted air venturi. The venturi accelerated the ram air pressure produced by forward flight through a narrowed opening. The instrument hoses were connected to the venturi at the point of lowest pressure, creating a vacuum that pulled a steady stream of air through the instruments. Although some VFR-only planes still use this arrangement, the trouble with this setup is that the amount of vacuum is low until certain airspeeds are reached, and the venturi can become ineffective due to ice buildup during inflight icing conditions. In the late 1930s, air pumps were developed that were engine-driven, creating air suction (or pressure) as soon as the engine was started. These early air pumps were lubricated with engine oil and would later be called “wet style” pumps. In the 1960s wet pumps were largely replaced with the “dry” pumps. Dry vacuum pumps are self-lubricating and have an oil-free exhaust flow that reduces belly deposits and provides a much cleaner source of air pressure on aircraft models that use the vacuum pump exhaust for inflating de-ice…
Many Cessna aircraft depend on a carburetor. Cessna Flyer contributing editor and A&P Jacqueline Shipe explains the operation of this fairly simple— and very reliable—invention. One of the most recognized carburetor manufacturers for the GA fleet is Marvel-Schebler. The company has been around a long time, having its beginnings in the early 1900s when George Schebler and his friend Burt Pierce worked together to design the first carburetor using a tin can with a flap to regulate airflow. They both went on to patent their designs, with Pierce calling his carburetor the “Marvel.” Both the Marvel and the Schebler designs were successful and used on a variety of engine types. In the early days of General Motors, the two merged and became known as Marvel-Schebler Carburetor Co. (Author’s note: Burt Pierce also designed the still-popular Marvel Mystery Oil through Marvel Oil Co., which he founded in 1923.) In the beginning, the Marvel-Schebler Carburetor Co. made carburetors for cars, boats, tractors and airplanes. The company has since changed hands several times, being purchased and resold by Facet Aerospace Products, Zenith Fuel Systems, Precision Airmotive and the Tempest Group (who called it Volare Carburetors until it acquired the Marvel-Schebler trademark in 2010).…
Loss of control is a hot topic among the NTSB, FAA and other aviation organizations that promote aviation safety. Last year, the NTSB named the prevention of loss of control in flight in General Aviation as one of its “Most Wanted” transportation safety improvements. The NTSB report issued in 2015 stated that “between 2001 and 2011, over 40 percent of fixed wing GA fatal accidents occurred because pilots lost control of their airplanes.” This is unacceptable and mostly preventable. All pilots should be aware of the possibility of loss of control and take the time to review actions to prevent it. One way is to study flight manual procedures specific to the aircraft you fly. Another is to be aware of common situations that can contribute to loss of control. As a former air carrier pilot, air taxi pilot and mechanic with inspection authorization, I will focus this article on equipment and mechanical malfunctions that can also contribute to loss of control. Preflight actions As aircraft control systems, flight management systems and electronics have advanced to make the task of flying easier, it is still necessary to have sufficient skills not only to fly the aircraft but to do all…
Fabric-covered planes in good condition are available, but you need to know what to look for. Aircraft have been covered in cloth since the Wright Brothers took flight, and the material had to be as light as possible yet strong enough to withstand the demands of flight. The standard material used in the early days was cotton or linen. Vintage aircraft typically had wood wings and steel tubing used in the fuselage. The materials The use of cotton or linen cloth is still approved; however, it is rarely used today because synthetic materials and improved processes are available. Synthetic materials and associated application processes not only reduce the amount of labor required, but also provide longer life, resistance to rot and fungus, and are safer in the case of fire (during material application, and while in flight). Polyester cloth specific to aviation applications is almost exclusively used in the recovering (or initial covering) of an aircraft today. Fiberglass cloth has been used as well, and other synthetic materials have been experimented with and/or are in development. The most important difference between newer synthetic materials and the original cotton and linen cloth is the fact that cotton is more difficult to…
A brief history of pneumatic boots, their operation and proper care. AS Jimmy Doolittle was demonstrating the technique of blind flying in 1929, work was being done by B.F. Goodrich and the National Advisory Committee for Aeronautics (NACA) to address airframe icing. William C. Geer, Ph.D., a retired chemist from the B.F. Goodrich Company, became interested in the problem of airframe icing when it caused a number of crashes of airmail planes. With IMC flight in its infancy at the time, airframe icing was seen as a barrier to progress. In the early 1930s, work by Geer and B.F. Goodrich focused on rubber coatings to inhibit the development of ice. How to get rid of the ice that did accumulate, despite the rubber boot and the concoction that was smeared on them to prevent the buildup, led to the idea of having inflatable tubes to knock off the ice. The de-ice boot was born. Structure, activation and various types The boots themselves are generally constructed with five or more spanwise tubes. These are created by layers of rubber laid up in such a way as to create the channels which expand when system pressure is applied to them. The inflation…
Do you know what instruments you can rely on to provide accurate information when the unexpected happens? A&P Mike Berry discloses what you absolutely need to know about your aircraft instruments. Aircraft instruments have been a part of aviation since the first flight of the Wright Flyer, which was equipped with a stopwatch, an anemometer (to measure wind speed) and a tachometer. With the increase of flight activity in the early years of aviation, aircraft instruments were invented to provide necessary information to pilots for precise control and navigation of their aircraft. As a pilot and aircraft owner, it is important to understand not only how aircraft instruments work, but also to be knowledgeable of the systems that they interface with. The maintenance and care of an aircraft, including its systems and required inspections, are tasks that the aircraft owner is responsible for—and they are not easy. In this article I will give some insight into instrument repair and replacement options as well as the maintenance and repair of systems that drive these systems. The basics, and some important questions All modern aircraft, whether the aircraft has digital or analog instruments, share the same basic pitot and static systems. These…
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