The pilot was flying on a cross-country flight to check on his son, who was participating in a mountaineering class in Talkeetna, Alaska.
He had exhausted the fuel in the left fuel tank and was operating the Aeronca 15-AC on the right fuel tank. He reported that he thought the airplane had about 12 gallons of fuel remaining.
After circling the camp twice about 8,000 feet mean sea level, the engine lost all power. In an effort to restore engine power, he switched fuel tanks, applied carburetor heat, and pumped the throttle. However, the engine sputtered and then lost total power again.
He turned the plane toward the nearest airstrip and was able to restore intermittent engine power by continuing to pump the throttle and rocking the wings.
While he was performing an emergency landing, the engine sputtered and had a short burst of power, which resulted in the plane overshooting the intended landing area and overrunning the departure end of the runway.
The Aeronca nosed over and sustained substantial damage to the rudder and left lift strut.
No fuel was found on the ground or vegetation at the accident site. About 8 gallons of fuel was removed from the right fuel tank, and the left fuel tank was empty.
A review of the airplane’s maintenance records revealed that its original bladder fuel tanks had been replaced with two 24-gallon aluminum-alloy fuel tanks and that this modification was approved by the FAA under its field approval process.
This process required that the maintenance information meet the original type certification basis for major alterations to aircraft, engines, and propellers certificated under the Civil Air Regulations. However, no fuel flow tests, usable/unusable fuel quantities, placarding, or flight manual supplement was referenced in the description of work when the tanks were installed or when the alteration was approved by the FAA as was required to meet the original type certification basis for the aircraft.
Examination of the wing fuel tanks revealed that the left tank’s internal baffle had half-moon lightening holes at the bottom of the fuel baffle, that the right tank’s internal baffle had lightening holes that started about 1 inch from the bottom of the tank, and that the baffle fit tight against the bottom of the right fuel tank.
Given the lack of lightening holes at the bottom of the right fuel tank’s internal baffle it is likely that the unusable fuel in the right tank would have been significantly greater than the unusable fuel in the left tank.
Each tank had a placard near the filler cap on the exterior of the wing indicating that the tank had 24 gallons of usable fuel. The fuel selector inside the cockpit had a placard indicating 36 gallons.
However, post-accident calculations estimated that the total usable fuel was actually 22.5 gallons and that the unusable fuel was about 4 to 5 gallons per fuel tank.
Due to maintenance personnel’s failure to conduct the required fuel system tests after the system was modified, the FAA’s improper approval of the fuel tank modification, and the inconsistencies in the construction of the fuel tank baffles and in the fuel-related placarding, the pilot would have had no clear idea of how much usable or unusable fuel was available in each wing tank.
Given the lack of mechanical deficiencies with the engine, it is likely that the engine lost power due to fuel starvation.
The NTSB determined the probable cause as maintenance personnel’s failure to perform required fuel system tests to ensure that the airplane met its original type certification basis after modifying the fuel system and the FAA’s improper approval of the fuel tank modification via the field approval process during which it did not ensure that the required fuel system tests were performed, which led to the pilot’s inability to determine the airplane’s actual amount of usable and unusable fuel and the subsequent loss of engine power due to fuel starvation.
NTSB Identification: ANC14LA038
This June 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Another calamity of errors. Improper placarding, inadequate installation and testing conducted and the FAA apparently accepting this as good. It reads like the gas tanks were built by two different parties because of the internal differences within them. Maybe the wings were from tow different ships. And there should have been a documented fuel flow test done before releasing the plane to service. .
There’s no indication that the FAA accepted anything. It’s up to the A&P, who has the required experience, properly trained, tested, and licensed. This individual is expected to do work to “acceptable standards”… which would include proper placards, proper testing, etc. The failure rests squarely with the A&P and the manufacturer of the flawed tanks.
This is not improper maintenance……….. it is improper procedures and field certification……. and a failure one everyone in the chain to think through the situation while making this modification…… nothing to do with improper maintenance.
Doesn’t ‘maintenance’ include work performed by a certified A&P… ie removing existing fuel tanks, replacing them with other, assuring the new tanks perform properly, assuring accurate and truthful placarding, and assuring the documentation and maintenance logs are accurate? The manufacturer produced a flawed product, but the maintenance tech failed to “Trust, but Verify”.
How can it be other than failure by the installer A&P failure who installed the new tanks to (1) accurately label the usable fuel in the cockpit at the filler necks after determining the true values? The NTSB reports the cockpit fuel selector placard said “36 gallons Usable”. Yet the placard on each individual tank said”24 gallons usable” at the filler neck (48 gallons total)… That is a discrepancy of 33%! After the accident the NTSB measured the capacity of each wing tank and discovered it was only 22.5 gallons total, with “4 to 5 gallons unusable” PER tank … i.e. 17.5 to 18.5 usable per tank?… Evidently, because of undiscovered manufacturing defects, the actual usable fuel in the right tank was quite a bit less than even the 17.5 gallons the NTSB calculated (Right Tank 22.5 gal total capacity – 8.0 in the aircraft after crash due to fuel starvation = 14.5 gallons actual usable) than 35 and 37 gallons since the NTSB reported that “approximately 8 gallons were in the right tank” when the aircraft suffered fuel starvation. These are big failures by both maintenance and manufacturers contributed to this crash. The pilot relied on maintenance personnel to do their job, and he was let down hard.
I agree 100% with John. I am always present when work is done as I have found that generally the certified A&P is not always very proficient. I have found they miss much that is important while fiddling with less important items.
I have had near crashes thanks to A&P mistakes…now I watch them like a Hawck often working with them.