The TR182 - One System at a Time: The Manual Wastegate Control

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2 months 3 weeks ago #3451 by STEVE ELLS
Hi Nathan,
I like your comprehensive, well written system break downs. I'm hoping you continue to post them.

Steve

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2 months 3 weeks ago #3449 by Nathan Wolfe
Hi All,

As I round out my first year with this aircraft, I've begun writing up my experiences with it. I decided to post them here. If you enjoy them, let me know. I'll continue to post. If you have systems you'd like to hear more about, let me know those as well. I don't profess to be an expert on everything airplanes, but I can do research and it's helping me learn.

I was planning on writing about either the Landing Gear System or the Built In O2 (Oxygen) system and my upgrades next. If you have any thoughts, let me know.

I hope you find this useful.

Thank you,

Nathan
N4657S
KLVK

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2 months 3 weeks ago - 2 months 3 weeks ago #3448 by Nathan Wolfe
My First Year as an Owner
Getting to Know the TR182… 1 System at a Time
The Manual Wastegate Control

Author: Nathan Wolfe


It’s been barely a year since I began my flying journey as an aircraft owner. Despite flying since 1989 and being a fractional owner on occasion, I’ve never owned an aircraft outright until I recently acquired a 1980 Turbo Skylane RG from Mark Pilkington at Skywagons.com, in October of 2020. About 10 minutes later my upgrade path started and it took me on an 8 month journey beginning with a full panel upgrade, ending when the aircraft came out of the interior shop. Had it been up to my wife, it would have gone straight to the paint shop but I’d had about enough of not flying my new baby at that point and in June of 2021 I drove over to KLVK (Livermore Municipal Airport) located in beautiful Livermore, California, to take her for a flight with of a freshly signed off annual and sporting a new weight and balance.

It was finally time… Sweet Mary Anne and I needed to get to know one another first. That’s what I named the plane, Sweet Mary Anne. It’s a long story for another writeup. Before I started ticking off the long list of flying, bucket list items now that I am flying in the widely varied terrain of California, I needed to get to know my plane.

We don’t like to believe it, but no airplane is perfect (Go figure!) and each has a list of special items, or characteristics that need special attention when flying and maintaining; and my TR182 is no exception. As a new owner, my list contained “watch items” like, Cessna Landing Gear, Nose heavy landing flare, Nose gear shimmy, tire flat-spotting tires caused by small tires, big brakes and over-zealous breaking, one of those dual Bendix mags, and my favorite to date… a turbo wastegate which is manually controlled by the pilot which, when I read about it, is apparently a complicated burden on the pilot.

While I’d agree that 1) the nose IS heavy in the flair, if you don’t trim aggressively, 2) the nose gear does have a tendency to shimmy on departure if you don’t lighten the nose a little (on my plane at least), 3) I begrudgingly admit I have personally flat-spotted the left main tire on the plane because the brakes are big, the tires are small and I was a bit overzealous trying to make that first turnoff, it was a small flat spot but yeah, <sigh>, I did it… 4) The manual wastegate is NOT on my list of things to worry about at all, and I’d suggest it shouldn’t be on yours either if you’re considering this aircraft.


Flying with a Manual Turbo-Normalizer:
For some reason, there is a widespread, misinformed belief about the Cessna Turbo-Normalizer and its manually controlled wastegate as implemented on the TR182. I’d admit, the aircraft is unusual in it’s engine configuration, flying a Carbureted, Lycoming O540-L3C5D with a Cessna-made, Turbo-Normalizer with manual wastegate. To my knowledge, it’s unique in the General Aviation world, but let’s not confuse unique, with poorly implemented or difficult to understand or operate.

For those needing a bit of background; The Lycoming 0-540 on this aircraft is Turbo-Normalized (not turbo-charged), which means that the system is designed to keep the MP at sea-level pressure ( 31” Max / 25” Top of the Green Arc) through FL200. Unlike a turbo-charger, it does not over-boost the engine to higher MPs (such as 40”). This makes for a long-lived engine that produces sea-level power all the way through its usable altitude range. In the case of the TR182, this isn’t done in the common way, through an electronically controlled system which automatically maintains your setting. Rather, it’s accomplished with a wastegate that the pilot manually controls via the throttle knob which is a little different… but only a little.

To really get an understanding for this, let’s walk through each phase of flight and note the differences.

The Manual Wastegate On takeoff: You set the MP to 31” on takeoff. That’s it!

Where things are different is that full throttle (31” MP) is typically at about the ½ throttle position as we are typically used to it. This means you don’t firewall the throttle once you hit the runway environment. It is possible to over-boost the aircraft if you get aggressive on the throttle, which will cause the pop off valve to make funny noises till you pull back on the knob a bit, but after about 2 or 3 departures you become more acquainted with the system. You will find it unusual that you only use ½ the throttle travel when setting 31” on takeoff, but I haven’t found this system to be any more difficult than setting departure power on any of the other airframes I fly. Even the FADEC controlled DA42 twin I fly requires a power validation check after you advance the throttles on the runway and this is basically what you are doing in the TR.


The Manual Wastegate in the Climb: Once you have your desired climb power set; you must advance the throttle a very-little bit every couple thousand feet to recover the MP inches lost to altitude.

You see, once the gear is up on a TR, it does climb like a scalded angel. Even near MTOW I get 1200ft per minute and things only slow down as you round into the Flight Levels where you’re down to 900’ per min at FL200 at near Max weight.
If you want to keep those amazing climb rates, about once every 1.5 minutes you'll need to add 2” MP (1” per 1000’ of climb). If not, you’ll see your climb rate fall off, just as you would in a normally aspirated engine. You’ll do this a couple times and then you’ll remember to keep it in your scan. Again, I didn’t find the adjustment difficult. In fact, it keeps the engine instruments in my extended scan, a pretty good outcome.

The Manual Wastegate in Cruise: Set your desired MP and generally you can forget it.
Just like any complex aircraft, the cruise check-list involves: Power, Prop, Cowl Flaps, Mixture. I find that I have to circle back to it every so often for a small adjustment as the pressure changes, not exactly burdensome.

The Manual Wastegate in Descent: This is the opposite of the climb, for every 1000’ of descent, you will have to remove 1” MP. This means a small adjustment every couple thousand feet. You’ll forget it once or twice and the result will be you driving downhill at 27” of MP, then you’ll remember to keep it in your scan.

The Manual Wastegate Below 6000’: The Turbo-normalizer isn’t a factor below 6000’. The aircraft can generate full power at those altitudes without it so it’s just like every other 182, just way faster due to the folding gear. An advantage is that there is no Turbo cool-off run after landing, which is common on many turbo charged aircraft.

In general, I’m really uncertain why this system is written about negatively at all. From a pilot perspective, it’s elegantly implemented via a single lever, the In flight workload in the aircraft is no significant increase over any other complex, high-performance aircraft and lower than many. It requires that you keep the MP in your scan on climb and descent but the aircraft speaks to you if you don’t, either in slow climb rate or higher descents speeds.

The dual-cam setup on the other end of the throttle cable that Cessna implemented to control the manual wastegate hasn’t been a maintenance problem, there are no ADs or SBs on the cam system I can find. I have read that A&Ps have complained about aligning it correctly, but when I speak to my A&P about it, the sentiment is, “meh. Every airplane has its more difficult systems. If you can read a service manual, it’s not that difficult.” I’ve been told to keep the cams greased with Lubriplate No 105, which I do at every oil change.

I will admit that my shop maintains 6 of these airplanes at KLVK alone and knows the systems well. I also fly pretty regularly putting in about 215 hours last year, which means it’s rare to have a week when my plane doesn’t fly and I’m sure that exercise helps keep things limber.

The Bottom Line
Overall my first year with the factory manual wastegate system has been unremarkable. Anyone who has the idea that this system represents a real increase in pilot workload has got it wrong. It just isn’t. The concept of operations is basic, learning to fly with it is simple, and even if you fail to make the adjustments on climb or descent the aircraft reminds you in a non-exciting way and you quickly learn to keep MP in your extended scan, something you should be doing anyway. If you are considering a TR182, and it is definitely worth considering, the manual wastegate control should not be a negative factor in your decision making.
Last edit: 2 months 3 weeks ago by Nathan Wolfe.
The following user(s) said Thank You: Troy Whistman

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