AOPA Pilot Magazine - December 2017 - 95

P&E
WHAT CAUSES POWER-LOSS ACCIDENTS?
Some surprising stats in FAA study
At the GA Engine Summit,
James Gray, an aeronautical
engineer in the FAA Engine and
Propeller Standards Branch,
updated attendees on his study
of more than 700 GA power-loss
accidents that occurred from
2000 to 2014. There have been
200 to 300 such accidents every
year, and roughly one in five
have been fatal (about 50 per
year). The number of nonfatal
power-loss accidents has been
slowly declining but the fatal
ones have been flat, causing the
percentage of fatal accidents to
increase in recent years.
As longtime owner of a
Cessna 310, I was shocked to
learn that the fatal power-loss
accident rate for piston twins
is more than twice the rate for
piston singles. Another shock:
The rate of power-loss accidents
for Experimentals is six times
that of certificated airplanes-
but a lot of those accidents have
occurred during the initial flight
test period, and the Experimen-

engine testing and aircraft testing. The
engine tests involve performance testing
of 20 engines of 15 different models, ranging from carbureted four-cylinder engines
to turbocharged, fuel-injected six-cylinder engines, plus some radials. Six of the
engines have been subjected to detonation
testing with each UL fuel and with mixtures of these fuels with 100LL (to evaluate
phased deployment). Four of the engines
went through 400-hour block tests using
each UL fuel, for a total of 3,200 hours.
The aircraft tests involve 10 aircraft models ranging from two-place light trainers to
high-performance twins and helicopters.
Getting these unleaded fuels approved
presents a unique regulatory challenge.
That's because the FAA doesn't certify
fuels; it certifies engines and aircraft to
operate on specified fuels. But in this
case, getting the UL fuels approved on a

tal community is working hard
to address that problem.
The study shows that most
power-loss accidents are caused
by fuel problems. During the
study period, 128 accidents were
caused by fuel starvation, 93 by
fuel exhaustion, and 43 by fuel
contamination. Another 31 were
caused by carburetor problems,
mostly carb icing. True mechanical problems were rare: cylinders
(23), connecting rods (16), magnetos (16), and fuel pumps (11)
topped the list.
While three-quarters of power-loss accidents were caused
by pilot misdeeds, maintenance
errors also played a nontrivial
role. These were classified in the
study as overhaul (57), assembly/installation (43), and repair
(12). The number of assembly/
installation-caused accidents has
been decreasing, but the number
of overhaul-caused accidents
has not. Think about that when
you're deciding whether to go
past TBO.
-MB

model-by-model basis for each engine and
aircraft is impractical. To get these new
fuels approved on a fleet-wide basis, the
FAA will require new statutory authorization. The FAA and industry are working
with Congress to achieve this. Stay tuned.

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ADS AND AMOCS

Much time was spent on a subject near
and dear to every aircraft owner's heart:
airworthiness directives. The Aircraft
Certification Service is responsible for
continued operational safety. The division gathers data on potential unsafe
conditions, performs a numerical risk
analysis to assess the frequency and
severity of the problem, collects candidate corrective actions, convenes a formal
corrective action review board to decide
what action is appropriate, and then
drafts the selected corrective action (AD,
www.aopa.org/pilot AOPA PILOT | 95

Go to

aopa.org/financemytraining
to apply today.

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AOPA Pilot Magazine - December 2017

Table of Contents for the Digital Edition of AOPA Pilot Magazine - December 2017
