On July 17, 1991, a Piper PA-31-310 Navajo (registration G-LYDD) operated by Janes Aviation was involved in an aviation accident near Lydd, United Kingdom during takeoff. No fatalities were reported. Investigators recorded the probable cause as: The exact cause of the double explosion in the right wing could not be determined with certainty. A possibility was that the non-wetted areas of the tanks had become slightly porous during the time that the aircraft had not been in use and consequently may… This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A).
During takeoff roll on runway 22, at about 60 knots, a loud report was heard and the outboard section of the right wing disintegrated. The crew aborted takeoff, stopped on the runway, and exited uninjured. The aircraft was damaged beyond repair.
Incident Overview
An aircraft that had been in storage for over two years and was recently being worked on was being ferried with two pilots on board. During the takeoff roll on runway 22, at a speed of approximately 60 knots, a loud report was heard. The outboard section of the right wing then disintegrated. The crew immediately abandoned the takeoff procedure and was able to bring the aircraft to a stop on the runway. The pilots exited the cabin and were uninjured. However, the aircraft sustained damage that rendered it beyond repair.
Investigation Findings
The investigation into the incident determined that the exact cause of the double explosion in the right wing could not be established with certainty. A possibility was identified: the non-wetted areas of the fuel tanks had become slightly porous during the extended period of inactivity. When the tanks were filled to capacity, small leakages of fuel may have occurred through these porous areas. The resulting fuel vapor could then have migrated outboard around the edges of the ribs at the end of the tank bay, leading to the explosion and subsequent wing disintegration.
Probable cause
The exact cause of the double explosion in the right wing could not be determined with certainty. A possibility was that the non-wetted areas of the tanks had become slightly porous during the time that the aircraft had not been in use and consequently may have allowed small leakages of fuel through the porous areas when the tanks had been filled to capacity. The resultant vapour could then have migrated outboard around the edges of the ribs at the end of the tank bay.