A Mooney M20K aircraft (G-OSUS) had been flying for approximately 15 minutes and was in level flight when the baggage door opened and detached. It struck the right tailplane and remained wrapped round the leading edge near its tip. This caused the pilot control difficulties and increased drag. The pilot declared a MAYDAY and made a successful emergency landing at Membury Airfield.
The investigation found the safety clip for the internal emergency operating handle of the baggage door was not correctly installed, so instead of holding the handle closed it held it in a slightly open position. During the flight, it seems most likely that this handle moved sufficiently towards the open position to disengage the shoot bolts from the door frame allowing the door to open. It could not be determined when the safety clip was incorrectly installed or why it had not been noticed.