Aviation Safety Corner
GREETINGS! For this month's topic, I will continue discussing, "Open-Door Debacle." The result
of a door opening in flight too often is a crash. It shouldn't be that way. This is Part II of IV.
Let's begin our discussion with "Cargo Doors." When a cargo door opens in flight, the effect on the aircraft can be more pronounced, particularly if the door is on the forward fuselage or nose, or in the wing or engine nacelle.
There can be a pronounced disruption of the aerodynamics, making the aircraft more difficult to fly. The door may separate and strike things behind it. There have been cases in which doors, and items inside the cargo bay, either hit the tail or went through spinning propellers. The damage in these cases was significant and, coupled with pilot dis-traction, caused several crashes.
In pressurized aircraft, an open door can cause all the above problems, as well as depressurizing the cabin. As a United Airlines 747 was enroute from Hawaii to New Zealand when the right door blew open and separated, taking a portion of the fuselage skin with it. Nine passengers were lost through the opening, and five occupants were seriously injured; but the pilots were able to regain control and return to Honolulu for an emergency landing.
Now, let's discuss, "On the Record." NTSB and the FAA General Aviation Data show 14 accidents involving cargo door openings in flight and 84 accidents or serious incidents involving cabin door opening since 1983.
In 33 of the cases involving cabin doors, pilots were so distracted that they failed to extend the landing gear. It is interesting to note that in almost half of these cases, the aircraft involved was a Beech 35 or 36 series Bonanza.
Typically, a door opened during or just after takeoff. In the confusion of returning for landing, the pilot "forgot" to put the gear back down. It is likely the sound of the gear-warning horn was lost in the din created by the open door.
The other 51 cabin-door cases had a variety of results. Aircraft overran runways or hit obstacles during subsequent attempts to land. Pilots lost con-trol in flight, apparently succumbing to panic and/or distraction. In none of these cases, however did the open cabin door make the aircraft unflyable.
Beech 35's and 36's were involved in nine of these 51 mishaps. Beech 23 "Musketeers" were involved in six, and Piper Aerostars in five. Single-Engine Cessna's were involved in five of the mishaps.
In addition to the 84 accidents since 1983, there have been 57 reported incidents of cabin doors opening in flight. There was no substantial damage or injury, and the pilots were able to land without further incident.
Most times we just do what needs to be done, fly the airplane and everything comes out okay.
Now, let's discuss, "Airline Mishaps." The air-lines report incidents of doors opening in flight about 20 times a year. Most of these events involve cargo doors, probably because of the way they work. Most cabin doors are some form of "pressure-plug" hatch.
They have to be pulled in slightly, turned, lifted or rotated, and then pushed back out. If the aircraft is pressurized, the force from the differential keeps the door closed. Contrary to what some non-aviation folks might think, as long as the pressure differential is there, you couldn't open a cabin door if you wanted to. Cargo doors, on the other hand, open outward. They are usually electrically driven and held in place by some form of roller-clamp assembly with hook-shaped clamps that engage and rotate around a bar. This system makes it possible to shut but not properly lock a cargo door. As the pressurization differential increases, the door can be forced open.
Now, in conclusion, remember "The most com-mon reason why doors open unexpectedly in flight is because they were never closed properly in the first place."
Don't miss next month's, Aviation Safety Corner, when we'll discuss, "Out of Control," and "Lack of Guidance." This will be Part III of IV.
Larry G. Harmon
FAA Aviation Safety Counselor