# NTSB DEN02LA096: Piper PA-25-235, N9791P, Boulder, CO, August 16, 2002 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: August 16, 2002, 13:40 local (19:40 UTC) - Place: Boulder, CO - Coordinates: 40.016944, -105.406112 - Nearby events: https://openairdocs.org/map.md?lat=40.0169&lon=-105.4061&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report April 18, 2003 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 55512 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN02LA096 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55512/pdf - Page: https://openairdocs.org/ntsb/DEN02LA096 ## Probable cause the pilot's inadequate preflight preparation, which resulted in fuel exhaustion and a subsequent loss of engine power, and his failure to maintain adequate airspeed during the forced landing, which resulted in an inadvertent stall/mush. Factors included the changing wind conditions, the high density altitude, and the lack of suitable terrain for a forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - nonmechanical, climb - preflight planning/preparation - inadequate, pilot in command (cause) - fluid,fuel - exhaustion - Forced landing, emergency descent/landing - In flight collision with terrain/water, emergency descent/landing - weather condition - other (contributing factor) - stall/mush - inadvertent, pilot in command - weather condition - high density altitude (contributing factor) - terrain condition - none suitable (contributing factor) ## Analysis The pilot said that he checked his flight time and fuel gauges (including fuel low level indicator light) before takeoff. While towing a glider, he experienced fuel exhaustion. He performed a forced landing to an open field, but the wind changed from a estimated 15 to 20 knots to no wind situation when he got close to the ground. The airplane stalled from about 8 or 10 feet, hit the ground, and nosed over. The engine was crushed back, and the left wing was separated from the fuselage. The calculated density altitude was 11,361 feet. ## Factual narrative On August 16, 2002, at approximately 1340 mountain daylight time, a Piper PA-25-235, N9791P, was destroyed during a forced landing following a loss of engine power near Boulder, Colorado. The commercial pilot, the sole occupant of the airplane, received minor injuries. Mile High Gliding Inc. was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the glider-towing local flight which originated from Boulder Municipal Airport approximately 30 minutes before the accident. The pilot had not filed a flight plan. The pilot said that he checked his flight time and fuel gauges (including fuel low level indicator light) before takeoff. He said that while towing a glider, he experienced fuel exhaustion. The pilot said he performed a forced landing to an open field, but the wind changed from a estimated 15 to 20 knots to no wind situation when he got close to the ground. He said that the airplane stalled from about 8 or 10 feet, hit the ground, and nosed over. The engine was crushed back, and the left wing was separated from the fuselage. The density altitude was calculated to be 11,361 feet. ## Aircraft - Registration: [N9791P](https://openairdocs.org/deregistered/N9791P-2004-03-31), registration cancelled 2004-03-31, S/N 25-7556104, built 1975 (OpenAirDocs) - Reported make and model: Piper PA-25-235 - Registry model: [Piper PA-25-235](https://openairdocs.org/model/piper-pa-25-235) (registry code 7102504) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: PA-25-235 - Airframe hours: 9478 - Engines: Lycoming O-540-GIAS 260 horsepower reciprocating - Damage: Destroyed - Flight: Other work use, Part 91 - Registered owner: Mile High Gliding Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, July 31, 2002, 98 hours before - Departed: 1V5, Boulder, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; injuries: minor; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review December 1, 2000; seat: center; flight hours: 1,417 total, 228 in this make and model, 1,361 as pilot in command, 242 in the last 90 days, 101 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 10 knots - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 99 °F, dew point 50 °F - Altimeter: 29.95 inHg - Observed at: BJC, 15 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20020816023699A](https://openairdocs.org/incident/20020816023699A), Aug 16, 2002: Piper PA25235, Boulder, CO, Substantial damage. (-23) This aircraft was conducting glider towing operations for approximately 30 minutes when the engine quit running. At the time the engine failed the pilot… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.