Loss of control Accident Piper PA-25-235 Pawnee N90866,
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ASN Wikibase Occurrence # 200273
 
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Date:Saturday 7 October 2017
Time:13:45
Type:Silhouette image of generic PA25 model; specific model in this crash may look slightly different    
Piper PA-25-235 Pawnee
Owner/operator:Skyline Soaring Club
Registration: N90866
MSN: 25-8156005
Year of manufacture:1981
Total airframe hrs:8265 hours
Engine model:Lycoming O-540-B2C5
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Destroyed
Category:Accident
Location:West of Front Royal-Warren County Airport (KFRR), Front Royal, VA -   United States of America
Phase: Initial climb
Nature:Banner and glider towing
Departure airport:Front Royal, VA (FRR)
Destination airport:Front Royal, VA (FRR)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
A glider was being towed for an introductory flight with the student in the front seat and the glider flight instructor in the rear seat. The glider flight instructor recorded the flight using a digital video camera. At the end of the first video, the tow plane and glider were on the upwind leg of the airport traffic pattern, during initial climb, and the glider was about 200 ft above ground level. The glider's airspeed indicated about 60 knots, and the glider's position relative to the tow plane was consistent with a high-tow position (that is, the glider was positioned slightly above the wake of the tow plane). The video then stopped for unknown reasons. About this time the instructor diverted his attention away from the tow plane. When the instructor looked back toward the tow plane, he did not immediately see it, but then noted that it was below and right of the glider.

Analysis and extrapolation of the tow plane and glider flightpaths revealed that during this time the tow plane turned toward the crosswind leg, stopped climbing, and began to descend while the glider continued to climb. The video then showed that the glider's nose then yawed right, and the yaw string was nearly 90° right. The glider's yellow tow rope release handle moved partially aft, and then a snapping sound was heard followed by the tow rope release handle extending further. The tow plane's elevator was in the "up" position at that time, and the glider then turned left and returned to the airport. The tow plane descended nose down into the backyard of a residence and was consumed by postimpact fire.

Microscopic examination of the tow rope separation revealed features indicative of overstress separation. This evidence and the snapping sound heard on the second video are consistent with the tow rope breaking about 1 second before the glider instructor fully pulled the tow rope release handle. The up-elevator and nose-down tow plane descent was consistent with the tension on the tow rope lifting the empennage of the tow plane. Examination of the tow plane did not reveal evidence of any preimpact mechanical malfunctions that would have precluded normal operation, and there was no evidence that the pilot attempted to cut the tow rope with the tow plane's guillotine.

The tow pilot had a history of hypertension, high cholesterol, and nonocclusive coronary artery disease. The pilot was taking medications to treat these conditions, but they were not considered impairing. According to the tow pilot's autopsy report, his heart was enlarged and he had mild-to-moderate atherosclerosis. Although the pilot's significant coronary artery disease increased his risk for an acute cardiac event, no evidence was found during the autopsy indicating that such an event occurred.

On the basis of the available evidence, the investigation could not determine if the tow plane pilot experienced a medical event during the accident flight or why the airplane stopped climbing at 200 ft rather than continuing to climb to the tow-release altitude.

Probable Cause: The tow plane pilot's loss of airplane control for reasons that could not be determined based on the available evidence. Contributing to the accident was the glider instructor's diversion of attention away from the tow airplane which resulted in his delay in releasing the tow rope once the tow plane was no longer visible from the glider cockpit.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA18FA006
Status: Investigation completed
Duration: 1 year and 5 months
Download report: Final report

Sources:

NTSB

FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=90866

Location

Revision history:

Date/timeContributorUpdates
08-Oct-2017 03:27 Geno Added
08-Oct-2017 18:16 Geno Updated [Time, Aircraft type, Registration, Cn, Operator, Source]
22-Mar-2019 19:12 ASN Update Bot Updated [Time, Operator, Nature, Departure airport, Destination airport, Source, Narrative, Accident report, ]

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