View Full Version : GTSIO's Handleing Tips

661 KTAS
17th May 2002, 01:14
Hi People,

I have heard a few horror stories about Continental's geared engines...... Does anyone who operates them have any hints/tips on how to do it 'propperly' ?!?

I have never flown anything with a GTSIO but do instruct on a light normally aspirated twin and want to instill the right operating habits in my students who may well one day fly something a little more tempremental than a IO360 !

Any thoughts would be great !

17th May 2002, 03:15
1. After start, do not advance throttle above 800 rpm until the oil pressure is above 35-40 psi.
2. Warm up the engine thoroughly before commencing takeoff...all temps and pressures well into the green...otherwise, very expensive repairs.
3. Advance the throttle slowly and smoothly to takeoff power and keep an eye on the MP to avoid overboost.
4. Ensure that the fuel flow at takeoff power is near the maximum (for combustion chamber cooling).
5. When in cruise, lean according to the POH. In addition, do not operate close to peak EGT. To do so results in accelerated exhaust maniford stress, an important consideration on twin Cessna aircraft subject to AD 2000-01-16.
6. Keep the CHT below 400F. 380 is about ideal.
7. When ready for descent, reduce throttle slowly from the cruise power setting about 5-6 inches of MP and continue reducing as required BUT NOT below 20 inches MP. At ALL times, keep the engine driving the propellor, NOT the prop driving the engine. This is true for all geared engines, not just Continental.
8. On descent, leave the mixture at the cruise power setting, or increase a small amount if necessary to level off at a normal power setting.
8. On landing, DO NOT increase the prop RPM until touchdown (or later). There is a Continental service bulletin about this, regarding the crankshaft counterweights.
9. If you MUST do engine-out training in GTSIO powered aeroplanes, reduce the throttle slowly to a zero-thrust setting.
Do not rapidly completely close the throttle. If a sudden complete power loss is required for training, reduce the mixture to ICO and leave the throttle advanced. When restoring power, reduce the throttle to just above the idle position, then advance the mixture.

If you treat the GTSIO engine properly, it will last a long time. Treat it roughly...expect to pay, BIG time.

Corporate Yank
17th May 2002, 03:24
Welcome to the world of some of the most misunderstood engines that have ever been bolted onto an aircraft. First off, read and understand everything your AFM tells you (common sense). Next, disregard all the old wives tales that you will invariably hear from the airport experts who probably have not ever flown these engines. And finally, search the site AVWEB and take to heart anything that you can find by the contributor named John Deakin. I think he knows more about the internal combustion engine than even the people who build them. If I can add a personal note, I spent a few years in the early 70's flying piper pressure navajos, and never had a problem with the large geared turboed lycomings, when a lot of other people had big time difficulties. Don't change throttle settings any faster than your manifold pressure needles can track "with you". If you're training with engine outs, do it with mixture cuts, never "yank the throttles". Doing so just might detune the crankshaft counterweights, setting you up for a catastrophic mechanical failure in the future. And lastly, be a real mother hen about leaning and CHT. Enjoy, they really sound great, almost as sweet as a round motor or a "flathead ford" with open pipes.-CY:)

big pistons forever
18th May 2002, 00:20
The last GTSIO powered aircraft I flew had over 1400 hrs a side with NO cylinder work. Temerature management is the key to the longevity of any turbocharged engine. Airspeed, mixture , and cowl flaps ( if fitted ) will all affect cylinder temps. The goal is to keep all the temps mid green from start up to to shut down. The problem is all the big flat sixes started life as 260 horsepower engines. They have been boosted up to 435 horses with the same cylinder sizes, resulting in a lot more heat and stresses on the cylinders, thus reducing their tolerance for the effects of less than optimal handling.

With respect to the C 421 Continental GTSIO 520 engine my SOP was as follows

1. Idle at 900 RPM, cruise at 1800 RPM which is supposed to be the most favorable harmonic for the gear train.

2. Allow the engines to fully warm up before exceeding taxi RPM

3. For mixture control,
a. aggressively lean on taxi to avoid plug fouling,
b. full rich for TO and climb
c . lean to 1440 TIT or 22.5 GPH on a digital ( shadin ) fuel
flow meter . This is about 3 GPH higher than book but is
only way to keep the cyl temps reasonable
d. leave the engines leaned on final approach unless a Go
Around is necessary

4. Plan your descents, gradually reducing power to about 24 in and then using drag to decend. Avoid as far as possible high airspeed low power situations. you should be able to fly the whole circuit or approach at 20 in , only reducing power in the flare.

5. Listen to the seat of your pants. If the engine is not humming smoothly it is probably too rich or too lean.

While this is specific to GTSIO engine, It is good that you create good habits in your students regardless of the engine type. The number one good habit I tried to impress on low time pilots was to avoid frequent power changes. to the point of limiting the more advanced students to three throttle movements from cruise to short final. This payed big dividends in forcing them to think ahead and fly accurately especially driving home the relationship between airspeed ,attitude, and aircraft configuration at any particular power setting. I felt this built good habits for when they moved to larger aircraft.

lord melchett
18th May 2002, 10:31
Rapid heat change - particularly 'shock cooling' - is the quickest way to knacker this engine. Technique on the Golden Eagle was to avoid moving the throttle as much as poss. (except in the flare!)

1. On a non limiting runway, consider reduced power T/O - the top of the MAP green arc is 32.5 ins so you could set the MAP at that and leave it all the way until the descent.

2. Descent. Contrary to other posts, the first thing to do is to leave the throttles alone. Tip the nose down and fly at the top of the green arc on the ASI until the CHT reduce to about 300F. THEN, and only then, start reducing MAP an inch at a time until you reach the radar pattern at about 25ins MAP. Clearly this needs to be planned well in advance to use height times 5 for descent planning.

3. Despite all this, the main weakness of this engine was oil leaks emanating from hairline cracks in the crankcase where the two halves bolt together.

Great sporty aeroplane though! Happy flying

18th May 2002, 14:41
Flew a 421B with 900hr a side engines(1200tbo) all around Europe/USA for 2 Summers plus 2 Transatlantic crossings. No engine problems whatsoever. If you get good ones that have not been abused and look after them you will get King Air performance at much less than half the price.
Dont let them idle too slow, you can actually HEAR the gear drives slapping around at low idle.
IMHO they are not a short trip aeroplane. Operations involving multiple short sectors and you are asking for a heavy bill at best.
One inch per minute or per 1000 feet mp reduction on descent whichever is longer, ALWAYS making sure that CHT stays in the green(pref right in the middle)
Allow extra distance and use cruise descents with a level segment to get the drag out and slow the A/c with minimum throttle changes to touchdown.
On my 421 I touched the props 3 times. After T/off to the top of the green arc for climb pwr. Set cruise at 1800(least resonance speed and luvly and quiet for the pax) and dont touch em again till on the deck, fully forward and start the stopwatch. I used to time 5 minutes at idle before shut down to let the turbos cool down otherwise oil gets baked on the shaft resulting in ....well its expensive anyway.
They are great engines, and they will run like clockwork if you are nice to them.
BTW the 421flight Safety course is really good(but expensive)
I have their manuals if you need any bits of technical info on 400 series Cessnas.

22nd May 2002, 02:55
I flew a couple of C421Cs for a FAR 135 operation quite a while ago. I wish I had some of the info in these posts at that time. I would like to add that we reduced the power no more than 2 inches MP per minute, which required early descents. During the winter if the plane was to be kept outside we had the oil heaters hooked up.

There was one post I disagree with. I would not use a reduced power takeoff no matter how long the runway is.

411A, where did you fly 421s in AZ?

22nd May 2002, 04:55
Have not flown a 421 in many years, but do own a 411A, a great machine at one third the cost. Our company now also leases a KingAir...even better. If things go according to plan, a JetStar will not be far behind.
And your comment about not using reduced power for takeoff...absolutely correct. If full throttle travel is not used, the additional cooling fuel is not available...for cooling. Not to mention not having full power available if one engine fails.