PEORIA, AZ, USA
N7403Z
PIPER PA-25-235
A WITNESS STATED THAT THE TOW PLANE ENCOUNTERED A 'DUST DEVIL' BETWEEN 100 AND 200 FEET AGL. HE THEN SAW THE GLIDER ENCOUNTER THE 'DUST DEVIL' AND GAIN ALTITUDE ABOVE THE TOW PLANE UNTIL THE TOW ROPE FORMED A 30- TO 45-DEGREE ANGLE. THE NOSE OF THE TOW PLANE THEN DROPPED AND THE AIRCRAFT DESCENDED TO THE GROUND. THE TOW ROPE WAS FOUND TO HAVE SEPARATED AFT OF THE TOW PLANE TOW RING. THE ROPE, WITH THE TOW RING ATTACHED, WAS LOCATED NEAR THE AIRCRAFT. THE REMAINDER OF THE ROPE, WITH THE GLIDER TOW RING ATTACHED, WAS FOUND BACK ALONG THE FLIGHT PATH. AN INSPECTION OF THE TOW PLANE HOOK RELEASE MECHANISM FOUND IT TO BE IN THE OPEN POSITION. THE MECHANISM OPENED ON IMPACT BASED ON THE SEPARATION OF THE TOW ROPE AND THE PROXIMITY OF THE ROPE TO THE TOW PLANE HOOK, AS WELL AS THE APPARENT SNAP BACK OF THE REMAINDER OF THE ROPE AWAY FROM THE CRASH SITE.
On May 11, 1995, at 1420 mountain standard time, a Piper PA-25- 235, N7403Z, was destroyed by ground impact and postcrash fire after takeoff at Peoria, Arizona. The aircraft was owned and operated by the Turf Soaring School and was performing a glider tow operation. Visual meteorological conditions prevailed and no flight plan was filed for the operation. The certified commercial pilot sustained fatal injuries. The flight originated from the Turf glider port at 1420 on the day of the accident. The pilot of the glider stated that he was approximately 40 feet agl when he saw a "dust devil" approaching from his left. He stated that the tow plane pilot turned left 15 to 20 degrees in the direction of the phenomena. He said he found his glider gaining altitude until it leveled off at 800 feet agl. He stated that, during the ascent, he lost sight of the tow plane and released the tow line. Another tow plane pilot stated that, while on climb out from runway 23L, the tow plane encountered a "dust devil" at between 100 and 200 feet agl. The tow plane pilot was observed to have leveled his aircraft attitude as he passed through the phenomena. He then saw the glider encounter the "dust devil" and begin to gain altitude until the tow rope formed a 30- to 45-degree angle above the tow plane in reference to the tow plane's longitudinal axis. Witnesses several hundred feet away on the ground observed the aircraft as it approached their position. They stated that they saw the tow plane appear to glide toward them, then abruptly nose over and impact the ground in a 30- to 40-degree nose-low attitude. They said the aircraft was engulfed in an instantaneous postcrash fire upon impact. They also stated that during this time they heard the tow plane engine quit, suddenly start again, rev up momentarily, and then quit for the second and last time prior to impact. A postaccident inspection of the aircraft revealed a 45-degree crush line on the prop spinner. One propeller blade had separated and did show evidence of a torsional twist. The remaining blade was bent back along the fuselage. The aircraft, from the propeller flange aft to the tail, had been completely engulfed by fire. The crankshaft was rotated and continuity to the accessory gears was established. The left and right magnetos and wiring harness were also destroyed by fire. The carburetor and fuel sump were fire damaged. There was no trapped fuel found during the inspection. Continuity of all control cables was established; however, no trim or flap settings could be determined. The three-strand tow rope was found to have separated approximately 10 inches aft of the tow plane tow ring. The 10-inch segment of rope, with the tow ring attached, was located 9 feet from the tail of the aircraft. The remainder of the 200-foot rope, with the glider tow ring attached, was found approximately 290 feet back along the flight path on a 30-degree bearing from the aircraft's final position. The final position of the rope exhibited turns and coils that placed the remainder of the rope in proximity with the glider tow ring. An inspection of the tow plane hook release mechanism found it to be in the open position. An autopsy was performed by the Maricopa County Coroner's Office. At that time toxicological samples were collected and submitted to the Civil Aeromedical Institute (CAMI). The results of the toxicological examination were negative for alcohol and all screened drug substances.
the pilot's inflight loss of control due to his delay in releasing the glider after the towed glider experienced an unplanned altitude gain on takeoff when it encountered a dust devil.
Source: NTSB Aviation Accident Database
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