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On July 7, 1994, at 0845 mountain daylight time, a Piper PA-23- 250, N5919Y, collided with the terrain shortly after takeoff from the Arco Airport, Arco, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the commercial pilot, the sole occupant, was fatally injured. The flight was destined for Burley, Idaho.
Witnesses reported that the pilot prepared for takeoff on runway 23, after completing a run-up. The airplane started its takeoff ground roll, however, the pilot aborted the takeoff after travelling approximately 600 to 700 feet down the runway. One witness stated that the left engine lost power just before the pilot aborted the takeoff. The pilot then taxied the airplane off the runway, and at this time, the witness stated that both engines were again producing power. The pilot taxied the airplane to the run-up area and performed another run-up check before taking off. After the airplane lifted off, the witness stated that the airplane suddenly and violently rolled to the right, then to the left, back to the right and then stabilized. Each time the airplane rolled to the right, the witness stated that the cabin door opened. The airplane continued the takeoff and attained an altitude of approximately 200 to 300 feet before making a sharp left turn and descending to the ground.
The airplane collided with level open terrain approximately one half mile from the end of the runway and 100 yards south of runway centerline.
The pilot's flight logbook indicates that the pilot had accumulated a total flight time of approximately 1,576 hours. Approximately four hours of flight time had been logged in the Piper PA-23-250.
One of the co-owners reported that the airplane had been purchased approximately one month prior to the accident. An annual inspection was performed prior to purchase on May 24, 1994. The engine log book sign-off for the left engine indicates a tach time of 3759.09 hours at this time. A log found in the airplane that was started on June 7, 1994 by the current owners, indicates that zero time since the annual was on the airplane at the time of purchase.
The co-owner stated that after a few hours of flight time on the airplane, the magnetos on the right engine went out of time. The attaching bolts were found loose. The engine logbook indicates that at the annual inspection, the magnetos had been removed for servicing and reinstalled. There are no logbook entries to confirm the magneto timing after the annual inspection.
The co-owner also reported that the left engine had experienced a loss of power when the throttle was brought to idle power. The mechanic inspected the idle mixture and made adjustments, however, this loss of power occurred again on future flights. The co-owner stated that the engine would continue to run if the boost pump was engaged.
The co-owner also stated that the switch for the right engine turbo-charger had been damaged prior to purchase and would not always function when the switch was engaged.
The co-owner reported that the cabin door had come open in flight on two occasions the year prior to the purchase. The mechanic who had worked on the airplane reported that with the door open, it would make a lot of noise and blow things around, but the airplane was controllable. The mechanic stated that he worked on the door to remedy a loose locking mechanism. There are no logbook entries to indicate when this work was accomplished.
The engine logbooks indicate that both engines were overhauled on March 23, 1977. Since the overhaul, the engines had accumulated a total time of approximately 500 hours. In the four and a half years prior to the accident, the airplane had accumulated a total flight time of 28 hours.
WRECKAGE AND IMPACT INFORMATION
The airplane was found laying flat on its belly with the nose of the airplane positioned on a magnetic bearing of 109 degrees. The landing gear had collapsed underneath. The surrounding terrain for several miles was flat plowed dirt and devoid of vegetation. Mobile sprinkler systems were in the area.
A ground disturbance of three craters were noted in the soft powdery dirt approximately 50 feet north of the main wreckage that correspond to the positioning of the landing gear. Both wings remained attached at the wing root, however, substantial downward loading to the wings was noted. Both outboard wing sections displayed leading edge tearing to the wing skin, and interior downward bending to the wing spar and ribs. The flaps and ailerons on both wings remained attached. The flaps were retracted. Control continuity was established from the outboard wing bellcranks to the cockpit area. The empennage remained intact with little damage noted to the horizontal and vertical stabilizers. The rudder and elevators remained attached at their respective hinges. Control continuity was established from the rear attachments, forward to the cabin area. The control yoke would not move due to lower impact damage.
Both engines remained enclosed in their respective nacelles and attached to the wing. The propellers remained attached to the crankshaft. The right side propeller blades exhibited rearward bending to one blade and the other blade was broken 15 inches inboard from the tip in a twisting configuration. The left engine propeller blades exhibited an almost identical bending deformation as the right side, except for one blade was twisted and bent forward at a point approximately 15 inches inboard of the tip.
The right side cabin door was found separated from the fuselage approximately five feet in front of and to the right of the nose. Both forward hinges were broken forward. The locking mechanism was found in the unlocked position, with the locking pins retracted. The locking mechanism was tested and found to operate normally. With the handle positioned to lock, the pins extended and remained extended when the door handle lock was pushed down.
The door frame was inspected and an indentation on the frame at the top rear locking port was noted. A similar indentation was noted at the bottom of the door frame locking port. The top forward frame did not appear to have damage to the frame near the forward locking port. These indentations to the frame correspond to the location of the locking pins on the door.
Both engines were inspected after the airplane was retrieved and moved to the airport. Both engine crankshafts rotated easily with gear and valve train continuity established. All spark plugs displayed normal operating signatures and the magnetos produced a spark. The fuel manifold valve was inspected on the right engine. The diaphragm was intact and pliable. No contaminants were noted. The fuel manifold valve on the left engine was inspected and a .6 inch long tear was noted near the valve plunger.
MEDICAL AND PATHOLOGICAL INFORMATION
Dr. E.E. Fisher at the Bannock Regional Medical Center Pathology Department, reported that the cause of death to the pilot was due to multiple trauma. Toxicological samples sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma City, Oklahoma, reported positive Quinine in the urine.
TESTS AND RESEARCH
The fuel manifold valve was bench tested at Precision Airmotive Corp., Everett, Washington. A flow test using 75 lbs/hr flow disclosed that little or no fuel flowed through the outlet ports, but exited the flow divider through the vent hole in the top of the cover.
The fuel manifold diaphragm from the left engine was sent to the National Transportation Safety Board Materials Laboratory for examination. The specialist reported that a bench binocular microscope was used to examine the area. The rupture contained two layers of rubber with woven strands of fiber between the rubber layers that were oriented in 0 and 90 degree directions. The rupture was oriented parallel to one of these fibers and tore through the strands that were perpendicular to the rupture. The specialist reported that it appeared that the area depicted in Figure 3 of the attached Metallurgist's Factual Report indicated a slow-moving crack produced during prolonged operation of the fuel manifold valve assembly. The fracture surface towards the ends of the rupture were smooth and appeared to have been made by a fast moving tear. It could not be determined when this tear began. The remainder of the diaphragm was undamaged and pliable.
The Piper Owner's Handbook states in Section III, that "in the event the cabin door is inadvertently unlocked in flight or the handle is not pushed forward and locked before take-off and becomes dislodged from its latching mechanism, the following procedures has been determined to be practicable for closing the cabin door while in flight, assuming adequate altitude has been attained. a. Retard throttles. b. Reduce airspeed to 90 MPH or less. c. Open storm window (left of pilot). d. Close door. e. Recover power and airspeed.
Other conditions, take-off, landing approach, and general low altitude flight will require action at the discretion of the pilot."
The wreckage was released to the co-owner on August 12, 1994. The fuel manifold valve and injector lines were released on October 13, 1994. The last known location of the wreckage was in the owner's hanger at the Arco Airport.