Vallee F50 at Catania on Apr 30th 2016, could not extend nose gear
Last Update: September 28, 2021 / 16:51:37 GMT/Zulu time
The airport of Catania was closed for about 5.5 hours as result of the accident.
Italy's ANSV have opened an investigation into the occurrence and dispatched investigators on site stating, the aircraft SE-LEZ landed without nose gear for reasons that will be established.
On Mar 16th 2017 Italy's ANSV released an interim statement in Italian, the technical portion of the report in English, reporting that the nose gear remained in its bay and did not move. The root cause of the nose gear not being able to extend had been incorrect assembly following a shock absorber seal replacement the previous day, which had required the shock absorber to be removed, disassembled, gland seals and separator piston seals being replaced, the shock absorber being serviced, before the shock absorber was re-assembled and re-installed. During reinstallation the valve housing was incorrectly mounted to the sliding member which resulted in the loss of the mechanical stop of the shock absorber's extension while the nose gear strut was retracted, as result the shock absorber's extended in the wheel well, the torque link straightened out while the nose gear was retracted after departure from Rimini, and the tyres entangled with the wheel well. The investigation is ongoing.
On Sep 28th 2021 Italy's ANSV released their final report concluding the probable causes of the accident were:
The accident was caused by the failure of the nose landing gear (nose gear up) due to over-extension of the shock absorber which caused interference between the tires and the NLG compartment and locked the NLG in a retracted position.
The over-extension was caused by the incorrect installation of some internal components of the shock absorber during the replacement of the internal seals the day before the accident.
The following factors contributed significantly to the improper activity conducted at maintenance:
- the insufficient experience of technical personnel in carrying out the maintenance tasks conducted on the NLG;
- the lack of controls on the operations carried out, deemed unnecessary by the CAMO engineering department;
- the lack of definition of roles and tasks during the planning phase of the maintenance work;
- the operational pressure on maintenance personnel, arising from the need to conclude maintenance operations quickly in order not to penalize the management of the aircraft;
- the insufficient clarity and lack of sensitive information in the maintenance tasks and related figures contained in the AMM, regarding the replacement of internal shock absorber seals, subsequently made clearer by the manufacturer;
- the reported black and white printing of the applied AMM procedures, which could have made the warnings in the manual barely legible.
The ANSV analysed: "The flight was conducted by crew members in accordance with the rules and procedures applicable to the type of emergency that occurred (failure to extend the Nose Landing Gear)."
The ANSV stated in their analysis: "maintenance personnel used the procedures on the AMM, two for replacing the seals inside the Shock Absorber of the NLG and another procedure for oil replenishment and nitrogen pressurization. ... The evidence that emerged from the investigation was of incorrect orientation of the Valve Housing and installation of the dowels in the "U shaped" holes instead of the round holes, their correct location."
Fokker had already released information about incorrect installations of the dowels in 1994 and again in 1997. In October 2004 another related message was sent to all operators.
The ANSV stated in their analysis of the maintenance works: "Analysis of the interviews of the three maintenance technicians involved in the removal and installation of the shock absorber revealed a lack of identification of roles and tasks within the team, together with a lack of communication among the team members." and later stated: "A decisive role in the manner in which the operations were carried out was played by the pressure exerted on the maintenance personnel, given the urgency, on behalf of CAMO, to restore the efficiency of the SE-LEZ within a few hours, thus avoiding that the designated crew went beyond the allowed working hours, in order to facilitate the redeployment of crew and aircraft on the same day to the Rimini base, from where the following morning the Rimini-Catania flight would have been operated."
B2075/16 - RWY 08/26 CLOSED DUE TO DISABLED AIRCRAFT REF AIP AD 2 LICC 2-1. 30 APR 10:49 2016 UNTIL 30 APR 14:00 2016 ESTIMATED. CREATED: 30 APR 10:49 2016
This article is published under license from Avherald.com. © of text by Avherald.com.
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