A dhc-6 captain reported that a right rear observer's emergency exit window blew out in flight at 2;...

Narrative:

Upon completion of climb checklist and reaching 2000 MSL; a rear observer announced that 'something is weird with this window'. Moments later; I heard a 'pop' and a gush of wind from the cabin. The emergency exit/forward right observer window had just departed the aircraft. Aircraft was controllable and the additional damage was superficial (additional plexi-glass flat panels and bubble windows were damaged as the object was departing the aircraft). No control surfaces were damaged and level flight was always achieved. Announced our position to the FSS; stated an 'urgent' situation onboard the aircraft citing the window departure; and requested an immediate landing. Landing was performed flawlessly and no injuries were reported by pilots or crew. Although the emergency exits are secured via a plastic safety cover; all observers swore that they never touched the handle. Perhaps an emergency exit was bumped upon entry / exit in the aircraft with the lever not totally seated. I'm honestly at a loss as to how this happened without physically pulling the lever. To my knowledge no damage was reported on the ground.

Original NASA ASRS Text

Title: A DHC-6 Captain reported that a right rear observer's emergency exit window blew out in flight at 2;000' after takeoff. The aircraft was returned to land with very slight additional damage and no loss of control.

Narrative: Upon completion of climb checklist and reaching 2000 MSL; a rear observer announced that 'Something is weird with this window'. Moments later; I heard a 'pop' and a gush of wind from the cabin. The emergency exit/forward right observer window had just departed the aircraft. Aircraft was controllable and the additional damage was superficial (additional plexi-glass flat panels and bubble windows were damaged as the object was departing the aircraft). No control surfaces were damaged and level flight was always achieved. Announced our position to the FSS; stated an 'urgent' situation onboard the aircraft citing the window departure; and requested an immediate landing. Landing was performed flawlessly and no injuries were reported by pilots or crew. Although the emergency exits are secured via a plastic safety cover; all observers swore that they never touched the handle. Perhaps an emergency exit was bumped upon entry / exit in the aircraft with the lever not totally seated. I'm honestly at a loss as to how this happened without physically pulling the lever. To my knowledge no damage was reported on the ground.

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	907799
Time
Date	201009
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	Twin Otter DHC-6
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	VFR
Component
Aircraft Component	Door Window
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Commercial
Experience	Flight Crew Last 90 Days 360 Flight Crew Total 2000 Flight Crew Type 1400
Events
Anomaly	Aircraft Equipment Problem Critical

A dhc-6 captain reported that a right rear observer's emergency exit window blew out in flight at 2;000' after takeoff. The aircraft was returned to land with very slight additional damage and no loss of control.