What happened
On January 31, 2020, a Partenavia P68B departed from Antwerp/Deurne Airport (EBAW) for a local flight following recent maintenance work. While the aircraft was climbing through 1,000 feet and performing a left-hand turn, the emergency exit window became detached from the airframe and fell to the ground. The falling component landed on a piece of wasteland approximately 15 meters from a passing vehicle. There were no injuries resulting from the incident, and the aircraft sustained only minor damage.
The investigation
Investigators examined the aircraft's maintenance history and the mechanical operation of the exit. The aircraft had recently undergone maintenance at a local agency, where the emergency window's security had been verified. However, the investigation revealed that the handle was found in the 'release' position.
Crucially, the investigation looked into the cockpit markings and placards. While the Pilot Operating Handbook (POH) specifies certain requirements, the actual aircraft lacked a clear, unambiguous marking to indicate whether the handle was in the locked or released position. Furthermore, the investigation found that the design of the handle did not provide sufficient protection against accidental movement.
Findings
- The primary cause of the window detachment was that the operating handle was inadvertently left in the 'release' position following maintenance, a condition that went undetected during the pre-flight inspection.
- The lack of clear identification for the handle's 'locked' versus 'released' positions acted as a contributing factor.
- The design of the emergency exit mechanism lacked adequate safeguards to prevent the handle from being moved unintentionally.