Narrative:

I departed torrance airport (toa) in a cessna 402 for short refresher flight. FBO instructor in capacity of observer was in copilot seat. My son was seated in cabin on left side (rear facing sat) -- the only (age 11) passenger. After normal departure from runway 29R, I turned southwest at the redondo beach shoreline and began leveling at 3000 ft MSL. At about 2 mi off- shore, the aircraft shuddered and wind noise increased. The cabin emergency exit window (right side of cabin) had departed the airplane. The cabin passenger was still buckled into the left hand forward cabin seat. I reduced power to 20 inches manifold pressure while the observer/pilot looked back for structural damage. No tail damage was observed, and the cabin passenger reported the window popped off and passed under the tail. We returned to toa for a normal landing on runway 29R. Aircraft flight characteristics remained normal. Tower asked aircraft on parallel IFR approach to break off and approved my request for runway 29R. Postflt inspection revealed the emergency release d-ring still clipped in place below the missing window, and no apparent reason for loss. I am certain the passenger (son) was seated and buckled in to the left cabin seat at all times from engine start to completion of flight. FBO mechanics report no known reason for window loss. There were no injuries or damage other than the missing exit window. Callback conversation with reporter revealed the following: the pilot said that after the initial inspection by the FBO's maintenance department the FAA inspected the aircraft and concluded that the passenger, the pilot's 11 yr old son, must have done something to cause the emergency exit window to depart. Another window was ordered from cessna for this 402. The second window was installed and inspected by the FBO's mechanics. The cessna 402 was test flown and the window departed. Another was ordered from cessna. The 3RD window was installed by the mechanics and inspected by both the FBO and the FAA. The cessna 402 was again test flown and again the window departed. Another window was installed test flown successfully and the aircraft was then sold to an overseas company. Cessna told the FBO and the pilot that they have never had this problem before. The reporter said that the FBO, later, told him that the 10000 hour aircraft was probably dimensionally changed and that may be a cause for the separations. This is not a pressurized model.

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Original NASA ASRS Text

Title: ACFT EQUIP PROB -- THE EMER EXIT WINDOW (OVERWING) DEPARTS FROM A LIGHT TWIN.

Narrative: I DEPARTED TORRANCE ARPT (TOA) IN A CESSNA 402 FOR SHORT REFRESHER FLT. FBO INSTRUCTOR IN CAPACITY OF OBSERVER WAS IN COPLT SEAT. MY SON WAS SEATED IN CABIN ON L SIDE (REAR FACING SAT) -- THE ONLY (AGE 11) PAX. AFTER NORMAL DEP FROM RWY 29R, I TURNED SW AT THE REDONDO BEACH SHORELINE AND BEGAN LEVELING AT 3000 FT MSL. AT ABOUT 2 MI OFF- SHORE, THE ACFT SHUDDERED AND WIND NOISE INCREASED. THE CABIN EMER EXIT WINDOW (R SIDE OF CABIN) HAD DEPARTED THE AIRPLANE. THE CABIN PAX WAS STILL BUCKLED INTO THE L HAND FORWARD CABIN SEAT. I REDUCED PWR TO 20 INCHES MANIFOLD PRESSURE WHILE THE OBSERVER/PLT LOOKED BACK FOR STRUCTURAL DAMAGE. NO TAIL DAMAGE WAS OBSERVED, AND THE CABIN PAX RPTED THE WINDOW POPPED OFF AND PASSED UNDER THE TAIL. WE RETURNED TO TOA FOR A NORMAL LNDG ON RWY 29R. ACFT FLT CHARACTERISTICS REMAINED NORMAL. TWR ASKED ACFT ON PARALLEL IFR APCH TO BREAK OFF AND APPROVED MY REQUEST FOR RWY 29R. POSTFLT INSPECTION REVEALED THE EMER RELEASE D-RING STILL CLIPPED IN PLACE BELOW THE MISSING WINDOW, AND NO APPARENT REASON FOR LOSS. I AM CERTAIN THE PAX (SON) WAS SEATED AND BUCKLED IN TO THE L CABIN SEAT AT ALL TIMES FROM ENG START TO COMPLETION OF FLT. FBO MECHS RPT NO KNOWN REASON FOR WINDOW LOSS. THERE WERE NO INJURIES OR DAMAGE OTHER THAN THE MISSING EXIT WINDOW. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE PLT SAID THAT AFTER THE INITIAL INSPECTION BY THE FBO'S MAINT DEPT THE FAA INSPECTED THE ACFT AND CONCLUDED THAT THE PAX, THE PLT'S 11 YR OLD SON, MUST HAVE DONE SOMETHING TO CAUSE THE EMER EXIT WINDOW TO DEPART. ANOTHER WINDOW WAS ORDERED FROM CESSNA FOR THIS 402. THE SECOND WINDOW WAS INSTALLED AND INSPECTED BY THE FBO'S MECHS. THE CESSNA 402 WAS TEST FLOWN AND THE WINDOW DEPARTED. ANOTHER WAS ORDERED FROM CESSNA. THE 3RD WINDOW WAS INSTALLED BY THE MECHS AND INSPECTED BY BOTH THE FBO AND THE FAA. THE CESSNA 402 WAS AGAIN TEST FLOWN AND AGAIN THE WINDOW DEPARTED. ANOTHER WINDOW WAS INSTALLED TEST FLOWN SUCCESSFULLY AND THE ACFT WAS THEN SOLD TO AN OVERSEAS COMPANY. CESSNA TOLD THE FBO AND THE PLT THAT THEY HAVE NEVER HAD THIS PROB BEFORE. THE RPTR SAID THAT THE FBO, LATER, TOLD HIM THAT THE 10000 HR ACFT WAS PROBABLY DIMENSIONALLY CHANGED AND THAT MAY BE A CAUSE FOR THE SEPARATIONS. THIS IS NOT A PRESSURIZED MODEL.

Data retrieved from NASA's ASRS site as of July 2007 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.