Aviation Safety Corner
GREETINGS! For this month's topic, I would like to discuss, "Anatomy of an Engine Failure." Examining
the nature of power losses on takeoff and how they can be avoided. This is Part II of IV.
Let's begin our discussion with, "Blocking the Flow." Twenty-seven accidents (10 percent) involved induction system difficulties. As may be expected, carburetor icing headed the list, but clogs/restrictions from other sources contributed significantly.
Carburetor icing was identified in 19 accidents. In most cases, either no carburetor heat control was available for use or the pilots failed to use carb heat at appropriate times. On problem, which should have been detected on run-up, was a disconnected carb heat hose.
The other cases of choked induction systems were primarily a result of poor maintenance and inspection. A shop rag was found in a carb airbox following anannual inspection of one airplane. Deteriorated and surprise, resulting in improper engine-out technique that led to off-airport forced landings.
In only one incident did a turbo come apart, resulting in pieces of the impeller damaging the engine. A worn exhaust clamp and a broken controller linkage were the cause of two accidents.
Propeller problems played a role in only three accidents. All were controllable-pitch props and had something to do with poor maintenance or manufacture. In one case, both props on a King Air went to near-feather position due to misadjusted ground idle stops.
In another accident, a homebuilder decided to shorten a propeller without examining the consequences or contacting the manufacturer. An overspeed condition (lot of rpm with no "bite") resulted.
Now, in Conclusion, Remember that the run-up is the last chance to check everything prior to asking the engine for all that it's got.
Don't miss next month's, Aviation Safety Corner, when we'll continue discussing, "Anatomy of an Engine Failure." Our Topics will be, "Avoiding Missed Beats." And "Harbingers of Trouble." This will be Part III of IV.
Larry G. Harmon
FAA Aviation Safety Counselor