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Guy:
From lengthy and controversial discussions on this subject, held over various Skymaster websites, you're gonna get two views. One side, including GAMI, believes that the ultra-precise injectors, custom drilled for each cylinder based on the heat of that cylinder (where it is on the engine), allows you to operate the aircraft safely at considerably lower fuel flow rates, thus saving lots of money. Specifically, these advocates believe that you can operate 50-100 dgrees LEAN of peak (you read that right, you lean the engine to peak EGT and then lean it some more).
A vociferous group of opponents claim that such operations, even with GAMI injectors, is an accident waiting to happen, because it will damage the engine and possibly cause an in-flight failure leading to a disaster. They further add that because you are not operating the engine per the POH (which forbids operation any leaner than 50 degrees rich of lean), if the engine fails there is no warranty. And they conclude by pointing out that the cost of these injectors is so high that it is hard to recoup the expense in fuel savings for the average pilot.
I'm a mechanical engineer (Master's from Caltech, spent 20 years on satellites and rockets and 10 years on jet engines) and have at times tried to referee this argument. Here's my take: the latter group -- the opponents -- are more right than the lean-of-peak (LOP) advocates. For average and even technically savvy pilots, they ought to stick with the factory recommendations. There are lots of documented cases where indeed LOP operation has led to failed engines; often NOT BECAUSE of LOP but because the pilot did not devote the additional attention needed for LOP operation.
Let me say it a different way. The POH way is rugged and tolerant of mistakes. Lets you fly the plane and enjoy the ride. LOP might work as GAMI and its advocates claim if ALL of the following things are just right: the right injectors were properly installed and checked out, a cylinder-by-cylinder diagnostic monitoring system is on board, and the pilot follows LOP procedures correctly AND monitors each cylinder like a hawk during each flight.
Since I'd rather enjoy the flight than act as a flight engineer, I opt for following the POH, and have done so in the two Skymasters I've owned.
Ernie Martin
Last edited by Ernie Martin : 03-03-03 at 11:46 PM.
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