Missing dip stick leads to fatal crash of Navajo

These November 2005 accident reports are provided by the National Transportation Safety Board. Published as an educational tool, they are intended to help pilots learn from the misfortunes of others.

Aircraft: Piper Navajo.

Location: Ankeny, Iowa.

Injuries: 2 Fatal.

Aircraft damage: Destroyed.

What reportedly happened: The aircraft was scheduled for a charter flight. A lineman serviced both engines with oil, but became distracted by an arriving aircraft that needed service and failed to put the dipstick back in the right engine oil filler tube.

The accident pilot had logged about 9,400 hours, including 5,700 hours in multiengine aircraft. He had about 500 hours in Navajos.

Witnesses reported that they did not see the pilot perform a preflight inspection. The pilot and passenger boarded the airplane, started it, taxied forward about 5 feet, then stopped abruptly and shut down both engines. The pilot got out of the airplane and closed the oil flap door on the right engine, then restarted the engines. The dipstick was found on the ramp a short time later. Approximately three minutes after takeoff, the pilot informed departure control that he needed to return to the airport due to an oil leak and trouble with the right engine. Radar data showed the aircraft heading back to the airport, but instead of making a straight-in approach to the runway it overflew the airport, entering a left turn. Airspeed decayed to 97 knots. The plane crashed in an agricultural field 1.5 miles east of the runway. The landing gear was down, flaps were extended to 20° and neither propeller was feathered.

The post-accident inspection of the airplane’s engines and airframe revealed no preexisting anomalies.

Probable cause: The pilot’s failure to preflight the airplane, the pilot’s improper in-flight decision not to expedite the landing, and the inadvertent stall when the pilot allowed the airspeed to get too low. Factors contributing to the accident were the lineman’s improper servicing of the airplane when he left the oil dipstick out and the subsequent oil leak.

Aircraft: Piper Cherokee.

Location: Mims, Fla.

Injuries: 2 Fatal.

Aircraft damage: Destroyed.

What reportedly happened: During cruise flight, the pilot reported to air traffic control that the airplane’s engine had ceased operating. He declared an emergency. He made a forced landing in a heavily wooded area and the airplane collided with trees.

The post-crash inspection found that all eight of the fasteners securing the no. 2 cylinder to the crankcase were separated. Metallurgical examination of the fasteners indicated they all separated due to fatigue cracking, probably due to insufficient clamping force. This led to separation of the no. 2 cylinder from the crankcase and a loss of engine power. Examination of the maintenance records showed that the engine had accumulated about 839 hours since a major overhaul approximately 13 years prior to the accident. There were no entries in the records indicating removal of the no. 2 cylinder since the major overhaul.

Probable cause: The loss of engine power due to improper installation of the no. 2 cylinder by maintenance personnel, which resulted in the separation of the cylinder as a result of fatigue cracking of the cylinder to crankcase fasteners.

Aircraft: Piper Arrow.

Location: Heathrow, Fla.

Injuries: 2 Minor.

Aircraft damage: Substantial.

What reportedly happened: During the preflight inspection the pilot noted that the fuel level in the left tank was nearly full and that in the right tank to be slightly above the tab. He made several touch-and-go landings and one full stop, landing at various airports, before proceeding back to the departure airport.

During descent, the engine began to run rough and lose power. Attempts to troubleshoot the problem were unsuccessful. He maneuvered for an emergency landing on a small road. The airplane hit the roof of a house and trees.

The post-crash inspection did not find any mechanical problems with the engine. Fuel was found in the fuel strainer, fuel lines and distributor valve. The fuel selector was found halfway between the right tank and the “off” detent.

Probable cause: A partial loss of engine power due to undetermined reasons resulting in a forced landing in a residential area.

Aircraft: Cessna T210M.

Location: Salt Lake City, Utah.

Injuries: None.

Aircraft damage: Minor.

What reportedly happened: During cruise flight the pilot leaned the mixture. As the plane approached the destination airport the pilot neglected to execute the pre-landing checklist, which included enriching the mixture.

During the turn from base leg to final, he noticed his airspeed was getting slow. He advanced the throttle but the engine lost power. The pilot then retracted the flaps to extend his glide, but still came down some 150 feet from the approach end of the runway. The aircraft nosed over.

The post-accident examination did not detect any engine malfunctions. Investigators determined that the pilot starved the engine by leaving the mixture lean.

Probable cause: A loss of engine power due to fuel starvation as a result of the pilot’s failure to use the before-landing checklist, resulting in failure to enrich the mixture.

Aircraft: Navion G.

Location: Imperial, Calif.

Injuries: 1 Fatal.

Aircraft damage: Destroyed.

What reportedly happened: The pilot held a private pilot certificate for single and multi-engine aircraft and had logged 2,000 hours.

He took off an hour before the accident and made several low passes over a barbecue gathering to wave at friends.

On the final pass the left wing of the aircraft hit a tree. Pieces of wing fell to the ground and the airplane flew into transmission wires, then hit the ground and burst into flames.

A post-accident examination revealed no mechanical issues with the airplane. Toxicological tests of the pilot showed a blood-alcohol concentration of 0.08, twice the legal limit allowed for piloting an aircraft.

Probable cause: The pilot’s failure to maintain clearance from a tree and transmission wires while performing a low altitude maneuver. Also causal was the pilot’s impaired judgment and performance due to alcohol ingestion.

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