​​​American Airlines, Inc. McDonnell Douglas DC 10-10 was damaged substantially when the aft bulk cargo compartment door separated from the aircraft in flight at approximately 11,750 feet mean sea level. The separation caused rapid decompression, which, in turn, caused failure of the cabin floor over the bulk cargo compartment. 

The separated door caused minor damage to the fuselage above the door and sub­stantial damage to the loading edge and upper surface of the horizontal stabilizer. 

There were 56 passengers and a crew of 11 aboard the aircraft. Two stewardesses and nine passengers received minor injuries.

We determined that the probable cause of this accident was the improper engagement of the latching mechanism for the aft build cargo compartment door during the preparation of the airplane for flight. The design characteristics of the door latching mechanism permitted the door to be apparently closed when, in fact, the latches were not fully engaged, and the latch lockpins were not in place. ​

​​​As a result of this investigation, we made the following recommendations: 

To the Federal Aviation Administration (FAA):

• ​​Require a modification to the dc-10 cargo door locking system to make it physically impossible to position the external locking handle and vent door to their normal door locked positions unless the locking pins are fully engaged. (A-72-097)
• Require the installation of relief vents between the cabin and aft cargo compartment to minimize the pressure loading on the cabin flooring in the event of sudden depressurization of the cargo compartment. (A-72-098)
• Require that the provisions of the McDonnell-Douglas Service Bulletin 52-49, entitled "doors-cargo-install revised 'closed loop' cargo door locking mechanism," be made mandatory by the immediate issuance of an airworthiness directive. (A-74-027) 
• Expedite your resolution of the cabin flooring venting problem so as to incorporate the flooring modification by airworthiness directives at the earliest practical date. (A-74-028)
• Amend the Airworthiness Directive of March 6, 1974, to require an improved viewing window and illumination of the lock pin area in order to permit full visual observation of the locking mechanism so that positive verification can be made of proper locking pin engagement. (A-74-29)