A dhc-8-100 flight compartment door fell off in flight after previously being removed during mainten...

Narrative:

While working on a dhc-8-100 (MEL 34-23-1); I removed the flight compartment door to remove the galley panel; to inspect the connector on the TCAS antenna. I reinstalled the door; performed operation of the door (I got into the cockpit and shut and latched the door. Opened the door; no problem noted. During flight; the flight compartment door came off. I did not enter on my trouble shooting form that I removed the door; because to remove the panel; the door has to come off; just like when you remove an access panel for the avionics bay or a floor panel to gain access to a black box.I know I should have put door removal on the form. I do not know what caused the door to come off. This was the last night of my shift and I was at the end of my shift when I put the door on. The flight crew door fell off during flight. Flight crew performed an air turnback.

Original NASA ASRS Text

Title: A DHC-8-100 Flight Compartment door fell off in flight after previously being removed during maintenance for access required to inspect a TCAS antenna.

Narrative: While working on a DHC-8-100 (MEL 34-23-1); I removed the flight compartment door to remove the galley panel; to inspect the connector on the TCAS antenna. I reinstalled the door; performed operation of the door (I got into the cockpit and shut and latched the door. Opened the door; no problem noted. During flight; the flight compartment door came off. I did not enter on my trouble shooting form that I removed the door; because to remove the panel; the door has to come off; just like when you remove an access panel for the avionics bay or a floor panel to gain access to a black box.I know I should have put door removal on the form. I do not know what caused the door to come off. This was the last night of my shift and I was at the end of my shift when I put the door on. The flight crew door fell off during flight. Flight crew performed an air turnback.

Data retrieved from NASA's ASRS site as of April 2012 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	846993
Time
Date	200908
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Night
Aircraft 1
Make Model Name	Dash 8-100
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Cockpit Door
Person 1
Function	Technician
Qualification	Maintenance Avionics Maintenance Airframe
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy

A dhc-8-100 flight compartment door fell off in flight after previously being removed during maintenance for access required to inspect a TCAS antenna.