Since overhauls fall into the four basic categories, then what are the “high priced” engine companies charging you for? Here are a few of the more popular advertising claims being made today. What do you think?
There are many claims being made about special “techniques” and exotic “procedures” that supposedly increase the reliability of a given companies overhauled engines. These claims are accompanied by high overhaul prices that are meant to cover the “cost” of putting this special technology into your engine. Now, stop and ask yourself something: If these companies really DID have a way to increase the reliability of an aircraft engine, wouldn’t the manufacturer be doing it and recommending it today? Of course they would.
Modern aircraft engines are, by design, very reliable. A big part of this reliability is due to the fact that engine manufacturers have set standards for the parts used in the engines, the acceptable condition of those parts and the method used to assemble those parts into a complete engine. Strictly following the manufacturers “new engine limits” guidelines at overhaul is the very best way to insure your engine will offer the same level of reliability it did the day it was brand new.
We will be the first to tell you there are specialty shops that can extract considerably more horsepower than is offered in a stock aircraft engine. High compression pistons, special profile camshafts and custom machine work in the combustion chamber and valve areas can produce significant horsepower gains. Some of the hottest experimental aircraft flying today make use of these modified engines to achieve their incredible performance. The key phrase here is experimental aircraft.
The engine manufacturers and the FAA have set rigid guidelines concerning modifications that can be made to a certified engine part. A few overhaul shops have elected to explore the “gray area” of these safety guidelines. Unless you fly an experimental aircraft, you should give serious thought to the reliability and liability issues of installing an engine in your aircraft that may have received modifications that could adversely affect its FAA certification.
One of the latest fads is “precision, dynamic engine balancing” for increased smoothness. We agree that reducing the vibration levels in any aircraft is desirable for numerous reasons. Increased passenger comfort, reduced airframe fatigue, longer avionics life.
The engine manufacturers also acknowledge this by establishing the guidelines for the balance of their engines’rotating components. If the engine overhauler follows these guidelines, which take into account the engine’s total rotating mass and relatively low operating RPM, your engine will run smoothly. The one thing you can do to significantly reduce vibration is insure the correct balance of the engine/propeller combination once they are installed back into your aircraft. So before you pay to have your engine “dynamically balanced” during overhaul, consider using that money to have your propeller/engine combination dynamically balanced as needed. You, your aircraft and engine will be much happier with the result.
The Bottom Line
After you cut through the “techno-babble,” fads, and marketing hype, one simple fact remains:
The best way to insure the same reliability, performance and longevity the manufacturer designed into your engine is to choose an overhaul facility that follows the guidelines set forth by the engine manufacturer and the FAA in order to comply with a “new limit overhaul.”