# NTSB ANC99LA137: Stinson 108-2, N97978, Chugiak, AK, September 9, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 8, 1999, 16:30 local (Sep 9, 1999, 00:30 UTC) - Place: Chugiak, AK - Coordinates: 61.409572, -149.169845 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.4096&lon=-149.1698&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 22, 2000 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 47399 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC99LA137 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47399/pdf - Page: https://openairdocs.org/ntsb/ANC99LA137 ## Probable cause A partial failure of the brake system. A factor associated with the accident was a leaking brake system. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - roll - landing gear,normal brake system - leak (contributing factor) - landing gear,normal brake system - failure,partial (cause) - ground loop/swerve ## Analysis The first pilot, a certificated flight instructor, was providing tailwheel transition flight instruction to the second pilot, a certificated private pilot. The first pilot said that eight successful stop and go landings had been accomplished prior to the accident landing. He said that while landing on runway 19 and during the landing roll, the second pilot applied the brakes. The airplane subsequently ground looped to the right, and the left wing struck the ground, resulting in substantial damage to the left wing. The first pilot said that brake pedals were only installed at the left side pilot position. After the accident, the second pilot related to the first pilot that during brake application, the left brake pedal 'felt mushy' and was less effective than the right brake. An FAA airworthiness inspector examined the airplane at the accident airport, and reported signs of brake fluid leaking from the left brake assembly. He added that disassembly of the left brake assembly revealed 'severely weathered and worn seals.' ## Factual narrative On September 8, 1999, about 1630 Alaska daylight time, a tailwheel equipped Stinson 108-2 airplane, N97978, received substantial damage while landing on runway 19 at the Birchwood Airport, Chugiak, Alaska. The first pilot, a certificated flight instructor, seated in the right seat, and the second pilot, a certificated private pilot, seated in the left seat, were not injured. The airplane was being operated as a visual flight rules (VFR) local area instructional flight under Title 14, CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed, and no flight plan was filed. During a telephone conversation with the NTSB investigator-in-charge on September 10, the first pilot reported that he was providing tailwheel transition flight instruction to the second pilot. He said that eight successful stop and go landings had been accomplished prior to the accident landing. He stated that while landing on runway 19 and during the landing roll, the second pilot applied the brakes. The airplane subsequently ground looped to the right, and the left wing struck the ground, resulting in substantial damage to the left wing. The first pilot reported that brake pedals were only installed at the left side pilot position. After the accident, the second pilot related to the first pilot that during brake application, the left brake pedal "felt mushy" and was less effective than the right brake. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office, examined the airplane at the accident airport on September 10. He reported signs of brake fluid leaking from the left brake assembly. He added that disassembly of the left brake assembly revealed "severely weathered and worn seals." ## Aircraft - Registration: [N97978](https://openairdocs.org/aircraft/N97978), registered now, S/N 108-978, built 1946 (OpenAirDocs) - Reported make and model: Stinson 108-2 - Registry model: [Stinson 108-2](https://openairdocs.org/model/stinson-108-2) (registry code 9230406) (OpenAirDocs) - Registry engine: [Lycoming 0-435A/0-435C](https://openairdocs.org/engine/lycoming-0-435a-0-435c) (registry code 41517, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-978 - Engines: Lycoming O-435 225 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Scott C. Marcy - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 3, 1998, 24 hours before - Departed: BCV, BIRCHWOOD, AK - Destination: BCV - Airport: BCV, Birchwood, runway 19, 4,010 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: right; flight hours: 7,800 total, 13 in this make and model, 7,500 as pilot in command, 125 in the last 90 days, 41 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 4 knots - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 45 °F ## 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 19990908025649A](https://openairdocs.org/incident/19990908025649A), Sep 8, 1999: Univar 1082, Birchwood, AK, Substantial damage. (.19) On September 8, 1999, about 2030 Alaska daylight time, a tailwheel equipped Stinson 108-2 airplane, N97978, received substantial damage while landing on… ## Other investigations on N97978 (2) 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. - [NTSB ANC93LA140](https://openairdocs.org/ntsb/ANC93LA140), Aug 8, 1993: Stinson 108-2 (N97978), Near Skwentna, AK, substantial damage. Probable cause: THE PILOT IN COMMAND'S INADEQUATE PREFLIGHT PLANNING AND PREPARATION. A FACTOR IN THE ACCIDENT WAS THE PILOT'S LACK OF FAMILIARITY WITH THE PARTICULAR AIRCRAFT'S PERFORMANCE. - [NTSB ANC71DAG24](https://openairdocs.org/ntsb/ANC71DAG24), Sep 14, 1970: Stinson 108-2 (N97978), Kenai, AK, substantial damage 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.