Tail Failure Results In Landing Accident

Location: Leesburg, Virginia, Accident Number: ERA21LA106
Date & Time: January 19, 2021, 10:55 Local, Aircraft: N5880L
Event: Flight control sys malf/fail, Injuries: None
Flight Conducted Under: Part 91: General Aviation – Instructional

An investigation report regarding a scary flight lesson in an American AA5 has been released, describing a crippled left elevator that collapsed from its outboard support assembly.

The report describes a routine training flight between a CFI and student, proceeding normally until the “airplane began shaking and buffeting violently and loudly. The control yoke was also shaking violently (left, right, fore, and aft), and the airplane was pitching up and down.” The instructor declared an emergency, hearing from a nearby aircraft that the AA5’s elevator was “flapping in the wind.” Luckily, the CFI managed to bring it home safely, though the aircraft incurred a nosegear collapse upon landing with such ineffectual rudder authority.

Post accident investigation showed that “left elevator remained attached to the bellcrank and supported at the inboard support bearing assembly, but the outboard support bearing assembly was separated from the outer rib of the left horizontal stabilizer, leaving the elevator displaced down from its normal position. The outboard support bearing assembly and a separated aft section of the outboard rib of the left stabilizer were not located or recovered. Relatively coarse striations intermixed with dimple features, consistent with cyclic overstress loading, were noted on the fractured outer rib of the left horizontal stabilizer.”

It’s unclear how much damage was incurred on the flight back, with the aft spar of the left horizontal stabilizer buckled. The NTSB believed it was the result of up and downward overstress incurred as the elevator experienced such harsh flutter throughout the descent. Overall, the primary cause appeared to be simple age, as the AA5 was more than 45 years old. Further examination of the horizontal stabilizer showed multiple cracks at the upper and lower bondlines, as well as bondline separation on the left and right sides. 

The end result was the issuance of a Service Bulletin, number 195, that required inspections on the wings, stabs, and fuselage to detect bonding separations in a similar vein.

FMI: www.data.ntsb.gov