ASN Aircraft accident ATR 42-500 F-GPYF Aurillac Airport (AUR)
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Status:Accident investigation report completed and information captured
Date:Sunday 25 March 2018
Type:Silhouette image of generic AT45 model; specific model in this crash may look slightly different
ATR 42-500
Registration: F-GPYF
MSN: 495
First flight: 1996-01-24 (22 years 2 months)
Total airframe hrs:35123
Engines: 2 Pratt & Whitney Canada PW127E
Crew:Fatalities: 0 / Occupants: 3
Passengers:Fatalities: 0 / Occupants: 48
Total:Fatalities: 0 / Occupants: 51
Aircraft damage: Minor
Aircraft fate: Repaired
Location:Aurillac Airport (AUR) (   France)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Paris-Orly Airport (ORY/LFPO), France
Destination airport:Aurillac Airport (AUR/LFLW), France
An ATR 42-500, operated by Hop! as flight 235 sustained damage to the left-hand wing/body fairing while on a flight from Paris to Aurillac, France. At the start of the descent the left main gear door separated from the aircraft.
A safe landing was carried out.

Probable Cause:

Contributing factors
The loss of the nut on the rear assembly of the left main gear door resulted in the separation of the left main gear door from the aircraft. However, the exact cause of the loss of the nut could not be determined.
However, examination of the left and right landing gear door fasteners of F-GPYF, as well as those of the HOP! fleet of ATR 42 aircraft, revealed defects in the conformity of these assemblies.
The investigation revealed errors in the generic maintenance documentation that may lead to the installation of out-of-date screw/nut combinations. The consequences of these deviations from good practice on the performance of the assembly could not be precisely determined during the investigation but may lead to a loss of function of the assembly.
Thus, the following combinations of organizational and human factors potentially contributed to the loosening and subsequent unscrewing of the nut on the rear assembly of the left main landing gear door:
- The ATR maintenance documentation concerning the choice of nuts to be used as an alternative to P/N IPC is complex and contains errors that could lead to an inadequate P/N nut choice ;
- The information on the torque to be applied on this nut and for all these alternatives was missing from the ATR maintenance documentation;
- The generic ATR maintenance documentation allows the reuse of nuts without checking their self-locking capacity. The work card for the removal/installation of train doors does not specify that it is a self-locking nut and does not require checking its self-locking capacity or its replacement by a new nut.

Accident investigation:

Investigating agency: BEA France
Status: Investigation completed
Duration: 2 years and 11 months
Accident number: BEA2018-0151
Download report: Final report



photo of ATR-42-500-F-GPYF
accident date: 25-03-2018
type: ATR 42-500
registration: F-GPYF

Video, social media

This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Paris-Orly Airport to Aurillac Airport as the crow flies is 423 km (265 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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