|PARACHUTIST SAFETY. As a result of its investigation, the NTSB urged the FAA to require that parachute jump operators use FAA-approved aircraft maintenance and inspection programs.|
This past September, the NTSB completed a special investigation on accidents involving aircraft used in parachute jumping. The U.S. Parachute Association asserts that there are between 2.2 million and 3 million parachute jumps yearly in the United States. The NTSB doesn’t collect statistics on jumper injuries and fatalities unless they’re associated with an aircraft accident. According to the NTSB, since 1980, 172 people, mostly parachutists, have been killed in 32 accidents involving parachute operations.
The NTSB became interested in doing the special investigation after a twin-engine de Havilland DHC-6-100 crashed in Sullivan, Mo., on July 29, 2006. The pilot and five parachutists were killed, and the other two parachutists on board received serious injuries. The turboprop had just taken off when flames began shooting out of the right engine. It flew to just above treetop level, then entered a right turn and crashed.
Investigators found that compressor turbine blades in the right engine had fractured and that the engines were being operated beyond the manufacturer’s recommended TBO (this was legal because the airplane was being flown under Part 91). The NTSB suggested that the developing fractures might have been detected during an overhaul. It also noted that the onboard single-point restraints used by the parachutists to fulfill the seat-belt requirement weren’t as effective as other systems, and likely contributed to the number of injuries and fatalities. Additionally, the airplane’s seating configuration hadn’t been properly documented.
Investigators found that the propeller autofeather system was inoperative and suggested that if it had been working, it might have helped the pilot feather the right prop and, thus, maintain aircraft control. The NTSB concluded that the pilot didn’t maintain adequate airspeed after the engine problem developed.
In its report, the NTSB identified three recurring safety issues in parachute aircraft accidents: inadequate aircraft inspection and maintenance; inadequate FAA oversight/direct surveillance of parachute operations; and deficient pilot performance in basic airmanship. Parachutists may accept the risks associated with jumping out of planes, but they shouldn’t have to accept undue risks while riding inside them. Parachutists are entitled to, at a minimum, an airworthy airplane, an adequately trained pilot and enough FAA oversight to ensure the safety of the operation.
The NTSB found that engines on planes used for parachute operations are often subjected to more wear and tear than those used in other Part 91 operations. They’re exposed to brief cycles of idle, takeoff, climbing, descending and landing, and often aren’t shut down between flights. In a service letter, Continental noted that engines used in parachute operations may require more frequent overhauls than are provided for by published TBO numbers. Pratt & Whitney excluded its turbine engines used on parachute aircraft from participation in programs to extend TBOs.
The NTSB expressed concern that jump operators are allowed to fly under Part 91 while advertising their services to the public and carrying annual passenger loads into the millions. It was also troubled that pilots don’t have to undergo initial and recurrent training specific to parachute flight operations.
In its safety recommendation, the NTSB called on the FAA to require jump operators to develop and use FAA-approved aircraft maintenance and inspection programs that include compliance with engine manufacturers’ service recommendations (e.g., TBOs and component life limits). The NTSB says the FAA should work with the U.S. Parachute Association to assist operators in implementing effective inspection and maintenance quality assurance programs. It wants the FAA to require jump operators to institute periodic flight checks to determine pilot competence, and to develop pilot training programs that address weight-and-balance calculations, preflight inspections and emergency and jump procedures for each type of aircraft flown. The NTSB also says that the FAA should be conducting, at a minimum, periodic on-site inspections of maintenance and operations. It noted that the FAA advisory circular “Sport Parachute Jumping” was published in 1991, and hasn’t been updated since.
In its review of the 32 accidents since 1980, the NTSB found that eight of the airplanes weren’t airworthy at the time they were dispatched. In nearly all of the accidents, the pilots held commercial or ATP certificates, yet didn’t perform adequate preflight inspections, do proper weight-and-balance calculations, maintain airspeed or properly execute emergency procedures—a fact the NTSB characterized as a “disturbing common denominator.” Twelve of the airplanes were loaded beyond their max allowable gross weights; nine of those were loaded outside of center-of-gravity limits. Twelve accidents involved loss of engine power, and nearly all of the pilots allowed the plane to stall.
On September 10, 1995, a Beech 65 crashed into a house about 2.5 miles from the municipal airport in West Point, Va. The ATP-rated pilot, 10 parachutists and a resident of the house were killed. The accident occurred in day VFR conditions.
Witnesses heard unusual engine sounds during takeoff. One person heard the engine stop for about four seconds, then regain power during takeoff. Black smoke trailed the airplane, and the witness saw it enter a shallow right turn that gradually increased to 70 to 80 degrees. The airplane then rolled into a left bank with a nose-down attitude of 45 degrees.
Investigators found that in 1975, the airplane crashed in Minnesota and was reported as destroyed; it was sold for salvage for $1 in June 1976. In November 1976, the airplane was again registered with the FAA. In 1995, the airplane was sold to the skydiving club that owned it at the time of the accident. Maintenance records didn’t indicate when the cabin seats were removed to accommodate parachutists. An FAA Form 337 had been filed indicating that floor-mounted seat belts were installed in 1990. The aircraft’s weight and balance had been recalculated, and logbook records were updated, but no such figures were found in the logbooks. More modifications were reported in 1995 via FAA 337s, but logbook entries didn’t match what was reported.
The airplane’s aft boarding door had been removed for sport parachute operations. Some Beech 65 airplanes were approved for flight with the cabin door removed, but not this one. The NTSB reported that the operator produced a “Flight Manual Supplement” stating that such door removal was authorized. The NTSB, however, reported that the document had been altered, and there were no records to indicate that the airplane had been flight-tested and authorized for flight with the door removed.
Teardown examination of the engines and propellers failed to find preexisting conditions that may have led to the accident. The airplane was found to have been about 170 pounds over gross weight, with the center of gravity about three inches aft of the limit. The NTSB’s report quoted from the FAA’s Flight Training Handbook: “Generally speaking, an airplane becomes less controllable, especially at slow flight speeds, as the center of gravity is moved aft. An airplane that cleanly recovers from a prolonged spin with the center of gravity at one position may fail completely to respond to normal recovery attempts when the center of gravity is moved aft by one or two inches.”
The probable cause of this accident was determined to be the pilot’s inadequate preflight/preparation, his failure to ensure proper weight and balance of the airplane, and his failure to obtain/maintain minimum control speed, which resulted in a loss of aircraft control after a loss of power in the right engine. The reason for the loss of power couldn’t be determined.
On June 21, 2003, a Cessna 182H was conducting an airdrop of parachutists near Cushing, Okla. A commercial pilot and five skydivers were on board, and day VFR conditions prevailed. Witnesses saw the airplane take off, circle while climbing to altitude and fly over the landing area, at which point the first parachutist jumped. The plane then made a left turn and “seemed to hang in the air,” according to a witness. The nose dropped, and the airplane started down. Two more parachutists then jumped out. When the airplane was about 300 to 400 feet AGL, a witness heard the engine power increase, but saw the airplane continue in a spin until impact. The pilot was fatally injured, two parachutists received serious injuries, two received minor injuries and one escaped injury.
Marks made in the ground and wreckage indicated that the airplane impacted in a flat attitude. There was no evidence of preimpact problems in the engine. The NTSB determined that the probable cause of this accident was the pilot’s failure to maintain airspeed, which resulted in an inadvertent stall/spin.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.