# NTSB ANC97TA148: Piper PA-18-150, N7054, Saint Mary'S, AK, September 13, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: September 13, 1997, 13:00 local (21:00 UTC) - Place: Saint Mary'S, AK - Coordinates: 62.05989, -163.290298 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=62.0599&lon=-163.2903&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 6, 1998 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 3085 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC97TA148 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3085/pdf - Page: https://openairdocs.org/ntsb/ANC97TA148 ## Probable cause The excessive pressure in the brake system resulting from heating of the recently serviced hydraulic fluid in the brake master cylinders, and the resultant locked brakes and inability to maintain directional control of the airplane. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - flare/touchdown - landing gear,normal brake system - pressure excessive (cause) - landing gear,normal brake system - locked (cause) - directional control - not possible, pilot in command (cause) - Nose over, landing - roll ## Analysis The 29-inch tundra tire equipped airplane was being landed on a wet, sandy, gravel bar. The pilot stated that the back seat heater had been blowing hot air on the brake master cylinders, which had just been serviced. At touchdown, the airplane began to nose over. The pilot attempted to add power and keep the tail down with airflow, but the airplane continued over onto its back. Skid marks were measured for 154 feet from the touchdown point. ## Factual narrative On September 13, 1997, at 1300 Alaska daylight time, a tundra tire equipped Piper PA-18-150 airplane, N7054, was substantially damaged when it nosed over during landing on a gravel bar, 10 miles east of Saint Mary's, Alaska. The commercial certificated pilot was uninjured. The airplane was operated by the State of Alaska, Department of Public Safety. The flight was conducted under 14 CFR Part 91 as a public use flight. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was filed with the operator. The airplane was accompanied by another public use airplane. The pilot stated that he was landing on a gravel bar. He stated to the NTSB investigator that the Gar-Aero 29 inch tundra tires contacted soft, wet sand, and the airplane began to nose over. He applied power to attempt to maintain airflow across the tail, but the airplane nosed over onto its back. In his pilot/operator report, the pilot indicated the brakes appeared locked, and there were skid marks in the sand for 154 feet. The pilot also indicated that hot air from the back seat heater hose was blowing on the brake master cylinders, which had just been serviced. ## Aircraft - Registration: [N7054](https://openairdocs.org/aircraft/N7054), registered now, S/N 18-8915, built 1971 (OpenAirDocs) - Reported make and model: Piper PA-18-150 - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-8915 - Airframe hours: 7635 - Engines: Lycoming O-320-B2B 160 horsepower reciprocating - Damage: Substantial damage - Flight: Public aircraft, Part 91 - Registered owner: Alaska Dept Public Safety - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 28, 1997, 62 hours before - Departed: BET, BETHEL, AK - Destination: BET, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 3,000 total, 2,900 in this make and model, 300 in the last 90 days, 100 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 2 knots - Visibility: 40 statute miles - Lowest ceiling: 4,000 ft overcast - Temperature: 50 °F - Altimeter: 29.00 inHg ## 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 19970913026609A](https://openairdocs.org/incident/19970913026609A), Sep 13, 1997: Piper PA18150, St Marys, AK, Substantial damage. Aircraft crashed on landing. (.4)the 29-inch tundra tire equipped airplane was being landed on a wet, sandy, gravel bar. The pilot stated that the back seat… 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.