# NTSB ANC04LA059: Piper PA-31-350, N4105D, Goodnews, AK, May 23, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 22, 2004, 16:05 local (May 23, 2004, 00:05 UTC) - Place: Goodnews, AK - Coordinates: 59.096668, -161.716659 - Nearby events: https://openairdocs.org/map.md?lat=59.0967&lon=-161.7167&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 28, 2004 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA-AL-ANC FSDO 03 - NTSB case key (mKey): 59374 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC04LA059 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/59374/pdf - Page: https://openairdocs.org/ntsb/ANC04LA059 ## Probable cause The pilot's inadequate weather evaluation which resulted in an in-flight encounter with severe turbulence, and his exceedence of the design stress limits resulting in overstress of the wings. A factor contributing to the accident was the presence of turbulence. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight encounter with weather, cruise - weather evaluation - inadequate, pilot in command (cause) - weather condition - turbulence (contributing factor) - terrain condition - mountainous/hilly - Airframe/component/system failure/malfunction, cruise - wing - overload - design stress limits of aircraft - exceeded, pilot in command (cause) ## Analysis The airline transport certificated pilot departed a remote airport in a twin-engine airplane. The airport is located on the coast of the Bering Sea, and has an area of low hills that are northwest of the airport. The pilot said the wind conditions were about 070 degrees magnetic at 25 knots, with gusts to 30 knots. After departure, the pilot reported that he initially climbed the airplane to about 1,200 feet, but as he approached the area of low hills, he descended to about 700 feet. At an indicated airspeed of about 185 knots, the pilot said that the airplane encountered severe turbulence for about 30 seconds, during which his radio headset was dislodged. Upon arrival at his destination, the pilot informed the director of maintenance that during the flight, the airplane encountered turbulence and appeared to have received damage to the wings. The director of maintenance reported that the airplane received structural damage that consisted of wrinkling and rippling of both of the upper wing surfaces, extending about 8 feet outboard from each engine nacelle. In addition, the elevator had wrinkling that extended about 6 inches inboard from each of the outboard hinge attach points. The closest official weather observation station is located about 32 nautical miles south of the accident site. An automated weather observation system (AWOS) was reporting in part: Wind, 110 degrees (true) at 17 knots, gusts to 27 knots; visibility, 7 statute miles; clouds and sky condition, 1,200 feet overcast. ## Factual narrative On May 22, 2004, about 1605 Alaska daylight time, a Piper PA-31-350 airplane, N4105D, sustained substantial damage when it encountered severe turbulence while in cruise flight, about 5 miles west of Goodnews, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country positioning flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by Grant Aviation Inc., Anchorage, Alaska. The airline transport certificated pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Goodnews Airport at 1600, and was en route to Bethel, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on June 2, 2004, the director of operations for the operator reported that the pilot was returning to Bethel without any passengers or cargo after delivering mail to Goodnews, which is located on the coast of the Bering Sea. When the pilot arrived in Bethel, he informed the director of maintenance that during the flight, the airplane encountered turbulence and the appeared to have received damage to the wings. On June 3, the director of maintenance reported that the airplane received structural damage that consisted of wrinkling and rippling of both of the upper wing surfaces, extending about 8 feet outboard from each engine nacelle. In addition, the elevator had wrinkling that extended about 6 inches inboard from each of the outboard hinge attach points. Due to the damage, the company removed the airplane from service. During a telephone conversation with the NTSB IIC on June 3, the pilot reported that during his flight to Goodnews, the wind conditions were about 070 degrees magnetic at 25 knots, with gusts to 30 knots, and the airplane encountered turbulence over an area of low hills that are north of the airport. When the pilot departed on the accident flight, he said he utilized runway 05 and began a right turn over the bay. He initially climbed the airplane to about 1,200 feet, but as he approached an area of low hills west of the airport, he descended to about 700 feet. At an indicated airspeed of about 185 knots, the pilot said that the airplane encountered severe turbulence for about 30 seconds, during which his radio headset was dislodged. He continued toward the coast and then turned northbound toward Bethel. After arrival in Bethel, he noticed the damaged wing surfaces. The closest official weather observation station is Cape Newenham Long Range Radar Station, which is located about 32 nautical miles south of the accident site. At 1555, an automated weather observation system (AWOS) was reporting in part: Wind, 110 degrees (true) at 17 knots, gusts to 27 knots; visibility, 7 statute miles; clouds and sky condition, 1,200 feet overcast; temperature, 52 degrees F; dew point, 46 degrees F; altimeter, 29.76 inHg. ## Aircraft - Registration: [N4105D](https://openairdocs.org/aircraft/N4105D), registered now, S/N 31-8252027, built 1981 (OpenAirDocs) - Reported make and model: Piper PA-31-350 - Registry model: [Piper PA-31-350](https://openairdocs.org/model/piper-pa-31-350) (registry code 7103110) (OpenAirDocs) - Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 31-8252027 - Airframe hours: 12446 - Engines: Lycoming TIO-540J2BD 350 horsepower reciprocating - Damage: Substantial damage - Flight: Positioning, Part 91 - Registered owner: Grant Aviation Inc. - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, May 19, 2004, 13 hours before - Departed: GNU, Goodnews, AK - Destination: PABE, Bethel, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: none; flight instructor, airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 15,000 total, 1,000 in this make and model, 12,000 as pilot in command, 200 in the last 90 days, 60 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 70° at 25 knots, gusting 30 - Visibility: 20 statute miles - Lowest ceiling: 10,000 ft overcast - Temperature: 50 °F, dew point 37 °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 20040522013179A](https://openairdocs.org/incident/20040522013179A), May 22, 2004: Piper PA31350, Goodnews Bay, AK, Substantial damage. (-23) Folllowing departure out of gnu encountered severe turbulance in cruise resulting in substantial airframe damage. ## Other investigations on N4105D (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 ANC00LA133](https://openairdocs.org/ntsb/ANC00LA133), Sep 15, 2000: Piper PA-31-350 (N4105D), Emmonak, AK, substantial damage. Probable cause: The pilot's continued operation of the airplane on unsuitable terrain, and the subsequent failure of the main landing gear torque link. Factors in the accident were rough and uneven runways, and… - [NTSB ANC97LA041](https://openairdocs.org/ntsb/ANC97LA041), Mar 27, 1997: Piper PA-31-350 (N4105D), Nome, AK, substantial damage. Probable cause: a fuel leak from an engine driven fuel pump which initiated an engine fire, and the fuel pump manufacturer's inadequate quality control of the fuel pump. 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.