# NTSB ANC02LA026: Interstate S-1B1, N48027, Big Lake, AK, March 29, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 29, 2002, 19:00 local (23:00 UTC) - Place: Big Lake, AK - Coordinates: 61.394443, -149.84555 - Nearby events: https://openairdocs.org/map.md?lat=61.3944&lon=-149.8456&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 26, 2002 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Anchorage FSDO - NTSB case key (mKey): 54429 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC02LA026 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54429/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54429 - Page: https://openairdocs.org/ntsb/ANC02LA026 ## Probable cause The separation of the exhaust system stack from the heat exchanger. A factor associated with the accident was an engine compartment fire. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - normal - exhaust system,stack - separation (cause) - Loss of engine power, descent - emergency - engine compartment - fire (contributing factor) - Nose over, emergency landing - terrain condition - snow covered ## Analysis Shortly after takeoff from a remote airstrip, the pilot noted a loss of engine power, and smoke in the cockpit. While attempting to return to the airstrip, the engine lost all power, and the pilot was forced to land on a snow-covered field. During landing, the main wheels broke through the crusted snow, and the airplane nosed over. A postaccident inspection disclosed that the exhaust stack had separated from the cabin heater's heat exchanger. The hot exhaust gasses burned associated ducts, wires, and the lower engine cowling. ## Factual narrative On March 29, 2002, about 1900 Alaska standard time, a wheel-equipped Interstate Arctic Tern airplane, N48027, sustained substantial damage during a forced landing about five miles southwest of Big Lake, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal flight under Title 14, CFR Part 91, when the accident occurred. The solo private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at Merrill Field, Anchorage, Alaska, about 1800, with a stop at Goose Bay, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on March 29, the pilot said he departed Goose Bay, en route to Merrill Field. He said he was less then half-way to Merrill Field when the cockpit started to fill with smoke, so he turned toward Goose Bay. En route the engine started to lose power, and he decided to make an emergency landing on a snow-covered field. Prior to landing the engine lost all power. When the airplane touched down on the field, the main landing gear broke through the crusted snow, and the airplane nosed over. During a telephone conversation with the IIC on April 1, the pilot said he found a broken weld on the airplane's engine tailpipe. The hot exhaust gasses escaping from the tailpipe into the engine compartment burned wiring and hoses in the compartment. He said there were no known mechanical problems with the airplane prior to the accident. The NTSB IIC inspected the airplane on April 8, and noted that the engine exhaust stack had separated from the cabin heater's heat exchanger. The pilot said the exhaust stack was missing when he landed. The hot exhaust gasses burned a hole through the lower engine cowling. There was a large burned area on both the interior and exterior of the lower engine cowling. All of the electrical wiring, below the level of the engine cylinders, was burned. The alternate air and heater air hoses/ducts were burned away. The paint on the lower portion, of the right side of the fuselage, aft of the lower engine cowling, was blistered. The belly of the airplane was covered with a thin layer of soot. The throttle cable, mixture cable, and fuel line were charred. The wing lift strut attachment points exhibited stress tearing of the fabric around the attachment points. The lift struts were bent. The fabric on the top of the fuselage showed stress fractures and tearing, and the top of the vertical fin was crushed. One blade of the two bladed, fixed-pitch propeller was bent rearward at the tip about 11/2 inches. ## Aircraft - Registration: [N48027](https://openairdocs.org/aircraft/N48027), registered now, S/N 11, built 1942 (OpenAirDocs) - Reported make and model: Interstate S-1B1 - Registry model: [Interstate S-1B1](https://openairdocs.org/model/interstate-s-1b1) (registry code 1850302) (OpenAirDocs) - Registry engine: [Franklin 4ACG199H3](https://openairdocs.org/engine/franklin-4acg199h3) (registry code 27010, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 11 - Airframe hours: 1447 - Engines: Lycoming O-320-E2D 150 horsepower reciprocating - Damage: Substantial damage - Fire: In-Flight - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 26, 2001, 48 hours before - Departed: Z40, Goose Bay, AK - Destination: PAMR, Merrill Field, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: none; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; last flight review January 5, 2002; seat: front; flight hours: 2,768 total, 550 in this make and model, 2,768 as pilot in command, 23 in the last 90 days, 8 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 19 °F ## Other investigations on N48027 (1) 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 ANC99LA030](https://openairdocs.org/ntsb/ANC99LA030), Mar 4, 1999: Interstate S-1B1 (N48027), Anchorage, AK, substantial damage. Probable cause: Fuel starvation resulting from the pilot not understanding the fuel system procedures, and selecting the improper fuel selector position. ## Docket (1 files) The files NTSB released with the investigation on July 24, 2002, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54429. 460 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 460 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40394803&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF 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.