Italian investigators have disclosed that incorrect maintenance was conducted on an Air Vallee Fokker 50’s nose-gear the day before the aircraft was forced to land with its nose-gear retracted.
The crew of the aircraft (SE-LEZ) had noticed an “unusual sound” during nose-gear retraction after it took off from Rimini on 30 April last year, says a technical analysis by Safran Landing Systems.
While the main landing-gear lowered on approach to Catania, the crew received a caution about the nose-gear, and carried out a low pass over the airport for a visual check. The tower controllers confirmed the nose-gear doors were open but the wheels were not deployed.
The pilots were unable to resolve the problem and the Fokker landed with its nose-gear retracted.
Safran has compiled the technical analysis to assist the inquiry by Italian investigation authority ANSV.
Maintenance records, it says, show that the nose-gear assembly underwent seal-replacement work on the day before the event.
During the process the shock-absorber was removed and disassembled. Seals were replaced and servicing of the shock absorber was carried out before it was reassembled.
But Safran’s analysis states that the “incorrect assembly” of the valve housing meant it was improperly oriented. The inquiry also found additional evidence of work having not been carried out correctly, including the overfilling of the shock absorber.
When the nose-gear retracted, the shock-absorber over-extended, causing the tyre to strike a bulkhead – the noise heard on take-off – and jam in the well.
“The contact between the tyre and the bulkhead meant that the gear could not be extended,” says the analysis.
Safran reviewed its technical publications but believes its instructions are “robust” and “written specifically to prevent incidences of incorrect assembly” of the valve housing and a resulting over-extension of the shock absorber. It believes that no corrections are required to the published assembly directions.
Source: Cirium Dashboard
