Narrative:

On climbout of a scheduled flight from iah to esf the F/a commented on the noise level in the back of the aircraft. This aircraft was an light transport with approximately 200 hours of total time. The first officer was the flying pilot on this leg. As we leveled at FL190, we both commented on a slight vibration that could be detected. At about the same time, the F/a again commented on the noise and now a vibration in the floor. With the vibration seeming to increase, the first officer and I made some power adjustments in an effort to isolate the problem. Power changes did not help and there were no other warning signs or lights. During the process of our investigation, the vibration abruptly stopped and a slight thud was felt. Since there were not any control problems or any other indications, we continued to our destination. Our conclusion was that we may have lost some sort of inspection panel. Upon our arrival at esf, I inspected the aircraft and found that a large access/inspection door had been torn from the underside of the aircraft. This door (approximately 18 inches X 36 inches) provides access to the right cooling pack. This door is hinged on one side and held in place by 3 or 4 snap type fasteners. When the door tore loose, it punctured the lower skin, leaving a whole approximately 1/2 inch in diameter. It should be noted that my first officer and I had just acquired this aircraft for our third flight that day. Since it was the first flight of the day for this particular aircraft, we did a complete preflight and found nothing loose or missing. Since our company began operating this particular aircraft type, several doors have been lost in flight, namely fuel access doors and hydraulic access doors. Our incident seems to have been the largest door to have come off in flight. It should also be noted that all of the doors that have been lost have the same type of fasteners. These fasteners are the type that are opened by pushing a button portion of the fastener and that action releases the latch. It is possible for these fasteners to appear locked, but may not be holding onto anything internally. It is my belief that for an aircraft that cruises at 275 KTS these fasteners are inadequate and poorly designed. I am concerned about additional problems that may be created when such doors tear loose. I am also concerned about those on the ground who may be targets of such falling doors.

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Original NASA ASRS Text

Title: LTT ACFT HAD LARGE INSPECTION DOOR DEPART THE ACFT IN FLT AFTER A PERIOD OF NOTICEABLE VIBRATION AND REPORT OF HIGH NOISE LEVEL IN CABIN.

Narrative: ON CLIMBOUT OF A SCHEDULED FLT FROM IAH TO ESF THE F/A COMMENTED ON THE NOISE LEVEL IN THE BACK OF THE ACFT. THIS ACFT WAS AN LTT WITH APPROX 200 HRS OF TOTAL TIME. THE F/O WAS THE FLYING PLT ON THIS LEG. AS WE LEVELED AT FL190, WE BOTH COMMENTED ON A SLIGHT VIBRATION THAT COULD BE DETECTED. AT ABOUT THE SAME TIME, THE F/A AGAIN COMMENTED ON THE NOISE AND NOW A VIBRATION IN THE FLOOR. WITH THE VIBRATION SEEMING TO INCREASE, THE F/O AND I MADE SOME POWER ADJUSTMENTS IN AN EFFORT TO ISOLATE THE PROBLEM. POWER CHANGES DID NOT HELP AND THERE WERE NO OTHER WARNING SIGNS OR LIGHTS. DURING THE PROCESS OF OUR INVESTIGATION, THE VIBRATION ABRUPTLY STOPPED AND A SLIGHT THUD WAS FELT. SINCE THERE WERE NOT ANY CONTROL PROBLEMS OR ANY OTHER INDICATIONS, WE CONTINUED TO OUR DEST. OUR CONCLUSION WAS THAT WE MAY HAVE LOST SOME SORT OF INSPECTION PANEL. UPON OUR ARR AT ESF, I INSPECTED THE ACFT AND FOUND THAT A LARGE ACCESS/INSPECTION DOOR HAD BEEN TORN FROM THE UNDERSIDE OF THE ACFT. THIS DOOR (APPROX 18 INCHES X 36 INCHES) PROVIDES ACCESS TO THE RIGHT COOLING PACK. THIS DOOR IS HINGED ON ONE SIDE AND HELD IN PLACE BY 3 OR 4 SNAP TYPE FASTENERS. WHEN THE DOOR TORE LOOSE, IT PUNCTURED THE LOWER SKIN, LEAVING A WHOLE APPROX 1/2 INCH IN DIAMETER. IT SHOULD BE NOTED THAT MY F/O AND I HAD JUST ACQUIRED THIS ACFT FOR OUR THIRD FLT THAT DAY. SINCE IT WAS THE FIRST FLT OF THE DAY FOR THIS PARTICULAR ACFT, WE DID A COMPLETE PREFLT AND FOUND NOTHING LOOSE OR MISSING. SINCE OUR COMPANY BEGAN OPERATING THIS PARTICULAR ACFT TYPE, SEVERAL DOORS HAVE BEEN LOST IN FLT, NAMELY FUEL ACCESS DOORS AND HYDRAULIC ACCESS DOORS. OUR INCIDENT SEEMS TO HAVE BEEN THE LARGEST DOOR TO HAVE COME OFF IN FLT. IT SHOULD ALSO BE NOTED THAT ALL OF THE DOORS THAT HAVE BEEN LOST HAVE THE SAME TYPE OF FASTENERS. THESE FASTENERS ARE THE TYPE THAT ARE OPENED BY PUSHING A BUTTON PORTION OF THE FASTENER AND THAT ACTION RELEASES THE LATCH. IT IS POSSIBLE FOR THESE FASTENERS TO APPEAR LOCKED, BUT MAY NOT BE HOLDING ONTO ANYTHING INTERNALLY. IT IS MY BELIEF THAT FOR AN ACFT THAT CRUISES AT 275 KTS THESE FASTENERS ARE INADEQUATE AND POORLY DESIGNED. I AM CONCERNED ABOUT ADDITIONAL PROBLEMS THAT MAY BE CREATED WHEN SUCH DOORS TEAR LOOSE. I AM ALSO CONCERNED ABOUT THOSE ON THE GND WHO MAY BE TARGETS OF SUCH FALLING DOORS.

Data retrieved from NASA's ASRS site as of August 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.