Flight and Incident Overview
On April 30, 2016, a Fokker F27 MK50, registration SE-LEZ, operated by Air Vallée as flight RVL233, departed Rimini airport at 06:48 hours with 18 passengers and 3 crew members. During the final approach to Catania airport, while stabilized on ILS Z RWY 08, the crew observed that the right and left main landing gear lights were green, but the nose landing gear (NLG) light was amber.
Initial Actions and Low Pass
The crew informed Catania Approach (ATS) of the problem and stated their intention to continue the approach for a low pass over the runway, followed by a standard missed approach, to request a visual confirmation of the NLG extension from the control tower. During the low pass, the tower reported that the nose gear was not extended, despite the nose gear compartment being open. After the pass, all landing gear lights, including the amber NLG light, extinguished.
Holding and Emergency Procedures
The aircraft proceeded to the INDAX point for a holding pattern at 3,000 feet, as agreed with ATS. During holding, the crew applied abnormal procedures for a nose gear unsafe down condition after selection, and subsequently alternate down procedures. Both attempts were unsuccessful. The crew declared an emergency and informed ATS of their intention to perform a final maneuver—a leveled 2G turn. The captain, who had been pilot not flying (PNF) until then, assumed pilot flying (PF) and executed the turn, but it did not result in NLG extension.
Second Low Pass and Final Approach
The crew informed ATS of the situation, including the number of passengers, fuel quantity, and absence of dangerous goods. They decided to follow a VOR procedure for RWY 26, followed by a visual approach for a second low pass to check the nose gear condition. After this second missed approach, the aircraft was instructed to perform an ILS procedure for RWY 08. Landing occurred at 09:34 hours with the main gear properly extended and locked, the nose gear in the "up" position, and the nose gear doors open.
Landing and Aftermath
A sequence of pictures from a video recorded by the Catania airport operator shows the aircraft landing with the nose landing gear not extended. The nose touched the ground only when the aircraft reached a speed sufficient to sustain it without NLG support. After the landing roll, the aircraft came to rest in the middle of the runway. Engines were shut down, and passengers and crew disembarked without further incident. Some passengers were transferred to the airport emergency room, and subsequently some were sent to a hospital for further examination; no passenger was reported to have sustained injuries as a result of the event.
Probable Cause
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.