B767-300 first officer reported the APU door departed the aircraft in flight.

Narrative:

On our flight we were heavily loaded on payload and thus going to be close to being over landing weight at our arrival airport. In flight the captain and I discussed a plan of action between ourselves and the check airman who was conducting a line check to ensure that we would meet our landing weight limitation. This included starting the APU approximately 1 hour remaining in flight to burn a little extra fuel and to request early descent and configure the aircraft early for landing if needed. As such; we started the APU [early] and requested a descent shortly thereafter and descended to FL240 from FL360. [About 30 minutes later] we received a shudder followed by a constant light vibration in the aircraft. Simultaneously; upon review of the situation I noticed and properly called out the EICAS caution message 'APU fault'. The captain called for and I properly completed the associated QRH items; and the PF slowed the aircraft eliminating the vibration. The APU did not re-light and was left off for the remainder of the flight; resulting in a normal approach and landing. Upon taxi in we attempted to start the APU once again. At this time; we once again received an 'APU fault' message; this time accompanied by an 'APU door' status message. We left the APU off and parked the aircraft. Upon further review on the post flight inspection it was found that the APU door had indeed departed the aircraft. At this point mx contacted the company and the flight crew notified the proper chain of command.

Original NASA ASRS Text

Title: B767-300 First Officer reported the APU door departed the aircraft in flight.

Narrative: On our flight we were heavily loaded on payload and thus going to be close to being over landing weight at our arrival airport. In flight the Captain and I discussed a plan of action between ourselves and the check airman who was conducting a line check to ensure that we would meet our landing weight limitation. This included starting the APU approximately 1 hour remaining in flight to burn a little extra fuel and to request early descent and configure the aircraft early for landing if needed. As such; we started the APU [early] and requested a descent shortly thereafter and descended to FL240 from FL360. [About 30 minutes later] we received a shudder followed by a constant light vibration in the aircraft. Simultaneously; upon review of the situation I noticed and properly called out the EICAS caution message 'APU FAULT'. The Captain called for and I properly completed the associated QRH items; and the PF slowed the aircraft eliminating the vibration. The APU did not re-light and was left off for the remainder of the flight; resulting in a normal approach and landing. Upon taxi in we attempted to start the APU once again. At this time; we once again received an 'APU FAULT' message; this time accompanied by an 'APU DOOR' status message. We left the APU off and parked the aircraft. Upon further review on the post flight inspection it was found that the APU door had indeed departed the aircraft. At this point MX contacted the company and the flight crew notified the proper chain of command.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1354213
Time
Date	201605
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	APU
Person 1
Function	First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe