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January 1, 1994
By Bruce Landsberg
There was a bang followed by a rush of air in the cockpit. The cabin door had unlatched and was trailing open about 3 inches — catastrophe or annoyance? It depends on what you're flying and when the grand opening occurred.
On many light aircraft, an open door is not much more than an attention-getter. In fact, this is a fairly common occurrence. Virtually everyone has had a door or window come open, usually during the takeoff roll or shortly after entering the climb. In a few cases, a latch may have failed, but most of the time, the pilot just didn't check door security.
The accident record shows that, in most cases, we have far more to fear from an overreaction on the part of the pilot than any aerodynamic nastiness from the aircraft. It is disconcerting when there is sudden noise and a rush of wind, but experience and flight tests have generally shown that airplanes handle an open cabin or baggage door with far more aplomb than the crew.
Some following examples from the AOPA Air Safety Foundation's Emil Buehler safety database show the potential for difficulty when a door is not secured. "During the takeoff climb, the pilot's door came open. The private pilot with two hours experience in the Beech Musketeer made a close-in traffic pattern to return for landing. During the base turn to final, the nose of the aircraft suddenly dropped, and the aircraft started to sink rapidly. It impacted the ground before a total recovery [could be] effected."
A similar scenario occurred in a Bonanza. "The pilot reported the cabin door opened during takeoff, and he returned for landing to close the door. The airspeed indicator showed 100 knots on a 1-mile final at which time the pilot retarded the throttle (normal approach speed is 80 knots). As the airspeed was reduced to about 90 knots, the pilot noticed a nose- high attitude and a sluggishness in the controls. The descent was continued at 85 knots when full flaps were applied. Approximately 100 feet from the runway, power was reduced to idle, and the aircraft stalled, apparently a result of the low airspeed, not the open door."
According to the Bonanza's pilot's operating handbook, "If the cabin door is not locked, it may unlatch in flight. This may occur during or just after takeoff. The door will trail open approximately 3 inches, but the flight characteristics of the airplane will not be affected, except that the rate of climb will be reduced. Return to the field in a normal manner. If practicable, during the landing flare-out, have a passenger hold the door to prevent it swinging open."
In a brief review of accidents resulting from open-door distractions, all of them occurred during takeoff, with one notable exception, which we'll discuss momentarily. Sometimes, it's the inadvertent stall that leads to grief, and other times, it's a rejected takeoff where there isn't quite enough room to stop.
A Baron pilot ran off the end of a 4,400-foot runway after the cabin door opened. The CFI said that more than half the runway remained at the time of the opening, which occurred at 91 knots — close to rotation speed. One attempt was made to close the door before the pilot decided to abort the takeoff. There was insufficient distance to stop, and the Baron slid off the end of the runway, collapsing the nose gear. The Baron POH has the same guidance as the Bonanza, which suggests that a quick trip around the pattern is a better deal than an attempted quick stop, unless there is ample runway.
In some airplanes, the problem is greater because of the door configuration. The Piper Aerostar has a clamshell door that opens on the pilot's side directly ahead of the left engine. It is reasonable to expect that the distraction resulting from an open door will be great due to the proximity of the propeller and because the door will probably open more fully based on the hinge location. The mental image is not pleasant. Shortly after takeoff, witnesses observed the aircraft in a steep left bank, descending until it crashed approximately 1,200 feet northwest of the departure end of the runway. According to the passenger, the pilot was distracted right after liftoff while attempting to close the door. The National Transportation Safety Board report states that the opening of the top section of the door in flight is not considered critical. The check list calls for the door to be checked closed prior to engine start, with the green locking pins properly displayed. The passenger stated that the pilot performed the cockpit check from memory.
A word of caution might apply on this accident. A top-hinged door that could scoop air, particularly if the aircraft was yawed to the open- door side, might cause some undesirable side effects.
In many cases, the resulting accident causes no serious injury, but occasionally, as noted here, the situation escalates from mere aggravation to tragedy.
Cabin doors are not the only source of unexpected openings; baggage doors can be equally troubling. A Cessna 421 fully loaded for a ski trip with the pilot and five passengers departed a 4,300-foot runway. Witnesses reported that just as the airplane became airborne, a nose baggage door opened.
Cessna, in a safety publication, Pilot Safety and Warning Supplements, noted that "generally, the flight characteristics of Cessna airplanes will remain normal with any baggage or cargo door open. The aerodynamic effects on an open door can vary, however, based on the location of the door...and the method used to hinge the door in relation to the slipstream. Baggage/cargo doors mounted on the side of the aft fuselage and hinged at the front will tend to stay nearly closed...and pose no special problems...as long as the airplane is not in uncoordinated flight...."
Nose baggage doors behave a bit differently but usually do not require a heroic effort from the pilot to save the aircraft. Cessna states, "Doors of this type...may pop open at rotation because of the increase in angle of attack and the slipstream pushing underneath the edge of the unsecured door. After the initial opening, the nose baggage door will tend to stay closed at higher speeds when leveled off and then gently open again when speed is reduced for landing."
The 421 turned downwind with the gear still extended, when witnesses reported that the engines were producing power, but they couldn't agree on exactly what had happened. Two stated that the left engine had stopped running, and two believed that the right engine had a reduction of power or rpm. Upon turning base, the airplane entered a descending left turn and collided with trees before sliding across a road and catching fire.
The investigation revealed that the left propeller was feathered but that the right baggage door appeared to be open. The left throttle was found to be two-thirds forward; the left prop control was in the full- feather position, and the right prop control was full forward. Both mixture controls were full forward.
It's obvious that there was some confusion as the pilot tried to configure the aircraft to keep baggage from tangling with the propeller. In a single-engine configuration, gear down, a fully loaded C421 is in for a hefty descent. The invariably clear thinking that follows an accident suggests that the flight would have probably fared better if both engines had been left running and a normal return made to the airport.
In airplanes with pressurized cabins, an open door is a greater hazard because it can let go with explosive force. Any nearby unsecured item that can fit through the opening will probably depart the airplane. This is one outstanding reason to keep your seatbelt fastened. Some airline incidents graphically illustrate the dangers of a sudden breach in the pressure vessel.
Closing doors sometimes requires a special technique, especially if the pilot has to leave his seat to get to the door. The crew of a Beech 99 that was deadheading back to base got an open-door annunciator, and the captain went aft to close the door. Whatever his plan, it didn't work, and he found himself outside the airplane, hanging onto the now fully open door. Unable to move, the captain hung precariously for 10 long minutes while the first officer headed for the nearest airport, fearing that he was now the pilot in command and sole occupant of the 99. The landing was uneventful, and the captain certainly gained a new respect for the line in the check list that reads "doors and windows — secure." That's good advice, and we should have an open-door policy thought out in advance.
See also the index of "Safety Pilot" articles, organized by subject. Bruce Landsberg is executive director of the AOPA Air Safety Foundation.
Aircraft Components and Gear,
GA Safety and Accidents,
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