Brazilian investigators have traced the main-gear collapse of a Trip Linhas Aereas ATR 72-200 at Altamira to fatigue in an undercarriage component.
Investigation authority CENIPA states that the fatigue, in an aft pivot pin, was initiated by an improper machining process.
Although the ATR 72 (PR-TTI) had landed smoothly at Altamira, after arriving from Belem on 21 February 2011, the left gear collapsed as the aircraft slowed to about 70kt.
It veered off the runway and came to rest with serious damage to the left-hand engine and propeller. None of the 51 occupants was seriously injured.
CENIPA says the gear assembly had been sent for overhaul in March 2009 to Av Industria Aeronautica but that some of the work had been outsourced to companies not approved by the Brazilian civil aviation authority.
The inquiry found a similar problem on the aft pivot pin in a second Trip aircraft (PR-TTJ), and states that the component would “probably” have not lasted the entire overhaul interval of 18,000 cycles, and might have resulted in a second accident.
CENIPA says the “lack of an effective supervision system” within the airline and other contractors allowed latent maintenance problems to remain unchecked and uncorrected.