Hi Everyone,

New TR182 owner here, just wondering what standard procedures everyone uses to lean during various stages of flight are. After takeoff i usually go to 25″/2400 for the climb portion and keep it there till i reach altitude and usually don’t really touch the mixture. This gives me somewhere in the range of 20-22 gph (according to my fuel flow gauge … who knows when it has last been calibrated though) and CHTs that vary from 360-390 across the different cylinders. I am wondering if there is much leeway to lean at all during the climb portion or the possibility of getting into the cylinder pressure red zone makes it not worthwhile? The strange thing to me is that the POH mentions to climb at full mixture, but for cruise, the performance tables do list 25″/2400 with something like a 14-15gph fuel flow, so definitely a 5-6gph less than full mixture. I am guessing this is doable because the plane is going faster and the CHTs can be cooler? Has anybody experimented with climbing slower and at a faster airspeed with a leaned mixture and therefore burning less fuel and possibly leaving less deposits from a too rich mixture?



Later for cruise (2200/22-23"), i can get my FF down to 13.5-14 gph, but if i go too lean then the CHTs are ok, but the TIT goes above 1500 so i go a bit richer. What limits do people usually use for max TIT?

Keep in mind non-turbo operations are completely different. Thanks!

-David

David,

I have never flown a turbo 182, but on the plane that I fly with turbo, the takeoff and climb procedure is with full mixture and 30 in of manifold. I guess CHT would be hotter if your reduce mixture. Why are you only getting 25" on yours? 25 is top of the green for NA birds. But turbos are supposed to go higher than that.

Rgs,

Patrick

Do I remember correctly that the TR182 has a carburetor? Are you able to go lean of peak for cruise? Many of the turbo Bonanzas cruise lean of peak, with a small loss in speed for a big reduction in fuel flow. Cylinders remain cool. They have precision, balanced fuel injectors.

A lot of Bonanza drivers do a cruise climb for better cooling and getting downrange faster. I use 5 degrees nose up or 120kts, which is about the same thing. I leave all 3 knobs full forward in the climb, which does not waste "much" fuel according to those who have done the experiment. Non-turbo, however and I have the altitude compensating fuel pump that does some degree of leaning for me automatically.

Some turbo Bo drivers do a LOP climb, that is possible but again requires a fuel system that can run LOP without roughness.

The turbo 182rg is a turbo-normalized design, and 25" is what is specified for climb, but the turbo will produce up to SL pressure of 30/31 inches.

The TR182 uses a carburetor, it is basically a 182RG that is turbo normalized. I wasn't asking so much for leaning in cruise (LOP isn't possible with a carburetor generally), but rather for climb. Again, why are those 5-6 gph needed when climbing at 2400/25" vs cruising at 2400/25", is it just because the extra airflow in cruise allows the CHTs to cool that much. Also, i'm sure every turbo system is different but do other types have a maximum TIT which they try to limit when leaning?

David,

Most turbo operators have a target TIT value for climb that is primarily predicated on engine compression ratio and desired % power for climb. The design of the turbo system will dictate how much pilot involvement is required to maintain that target TIT. The turbo RG 182s with which I am familiar use a direct mechanical wastegate control as well as a pressure carb so some of the advice from turbo bonanza operators will be slightly different than your experience.

Most (but not all) turbo installations include a limitation of maximum CONTINUOUS TIT. This limit is frequently 1650-1750*F.

The 1650 limit (1750 for inconel) is an exhaust system limit based upon the material of the exhaust system. Especially at high altitudes, you will often fry your cylinders before reaching these limits.

Running at 1575 to 1600 is fine should the CHT be good on the long term. I think the rule is that every 100 deg of TIT is a half life on your exhaust system. There is a trade off for everything!

25” and 2400 seems like a high cruise setting for a TR. It seems to me 23 square is about 68 percent?

Start very rich and slowly/incrementally work your way back to leaner mixtures until you find what produces 380 deg max continuous CHT using 400 deg as your do not exceed.

Keep in mind that CHT takes a while to settle in, unlike EGT or TIT which you can use for a quick cross reference once you know where your plane runs. Small changes, monitor for a few minutes.

This is a good situation to hire a good turbo savvy CFI!

If anyone mentions LOP to you with regard to a TR182 immediately ignore anything and everything they say, they are dangerous to your financial future and don’t have any idea what they don’t know, and should be asking questions, not answering them.

TR182 owner here. I take off at full rich, 31" throttle and I leave the throttle in and let MP drop to 25" as I climb. The TIT is ~1300F at this setting and I lean slightly to keep it there as MP drops.

Cruise is usually 2200/22"-23" at ~12.7 GPH and TIT is ~1530F. I don't let CHT's get above 370F and might have to open cowl flaps a notch or two at high ambient temps.

The 1650 limit (1750 for inconel) is an exhaust system limit based upon the material of the exhaust system. Especially at high altitudes, you will often fry your cylinders before reaching these limits.

Running at 1575 to 1600 is fine should the CHT be good on the long term. I think the rule is that every 100 deg of TIT is a half life on your exhaust system. There is a trade off for everything!

25” and 2400 seems like a high cruise setting for a TR. It seems to me 23 square is about 68 percent?

I like this technique, will try it out, less forgetting to reset the MP to 25" constantly during the initial climb.