It’s hard to argue the ‘single vs. twin‘ debate … especially with someone who had just put a single-engine airplane down off-airport following a catastrophic engine failure. This endless debate has no statistically provable answer (many twin-engine failures end with a successful single-engine landing and no accident report, and even some in-flight engine failures in single-engine aircraft end up with a glide to a runway and don’t land in the record books). I do have some information, however, that helps draw some conclusions about the relative safety of single- and twin-engine airplanes.
I track mishap reports involving piston-powered Beech airplanes for a number of pilot training organizations and individual subscribers. Here’s the information I have on these airplanes for calendar year 2003:
ENGINE FAILURES
Total reported: 43
Single-engine: 30
Multi-engine: 13
BY SCENARIO
ENGINE FAILURE IN FLIGHT
Total reported: 18
Single-engine: 15
Multi-engine: 3
ENGINE FAILURE ON TAKEOFF
Total reported: 9
Single-engine: 8
Multi-engine: 1
ENGINE FAILURE ON APPROACH/LANDING
Total reported: 5
Single-engine: 1
Multi-engine: 4
FUEL STARVATION/EXHAUSTION
Total reported: 7
Single-engine: 6
Multi-engine: 1
ENGINE FIRE IN FLIGHT
Total reported: 4
Single-engine: 0
Multi-engine: 4
DEFINING THE STATS
Of the 43 reported engine failures in Beech piston airplanes in 2003, 70% were in single-engine airplanes while 30% were in twins. Inside Information: Considering the relative number of piston Beechcraft produced, singles vs. twins, a higher-than-expected percentage of twin-engine Beechcraft were involved in engine-related accidents. This suggests (at least on the surface) that the second engine does not reduce the rate of engine-related mishaps … and may actually make them more likely. However, this might be slightly offset by the typically higher utilization rate of twins vs. singles.
Twice as Likely to Fail?
There’s a strong case to be made that the twin-engine pilot is twice as likely to experience an engine failure as his or her single-engine counterpart. Pilots as far back as Charles Lindbergh used this logic to explain their preference for single-engine airplanes.
If this thinking is true (and it is logical), than the above analysis suggests that a little more than half of all multi-engine power plant failures result in a mishap. Hence, although having the second engine is not a panacea for engine-related accidents, the possibility exists that something can make up for the increased likelihood of an engine-related accident in twins, allowing the pilot to realize the safety benefit of the second engine. That “something” is improved pilot training and proficiency. Next time, we’ll take a look at some of the very specific differences in the pilots and the scenarios they face when engines fail in light twins and light singles.