# NTSB ANC15LA034: Piper PA 22, N2828P, Skwentna, AK, June 1, 2015 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: May 31, 2015, 20:00 local (Jun 1, 2015, 04:00 UTC) - Place: Skwentna, AK - Coordinates: 61.701389, -150.936111 - Nearby events: https://openairdocs.org/map.md?lat=61.7014&lon=-150.9361&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report September 8, 2015 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA - ADs cited in the narratives: [AD 73-09-06](https://openairdocs.org/ad/73-09-06) (OpenAirDocs) - NTSB case key (mKey): 91283 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC15LA034 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91283/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91283 - Page: https://openairdocs.org/ntsb/ANC15LA034 ## Probable cause The pilot's failure to follow the airplane's operating limitations by rapidly opening the throttle, which resulted in a loss of engine power. Contributing to the accident was the pilot's decision to maneuver the airplane at low altitude even though he was not taking off or landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: powerplant parameters](https://openairdocs.org/ntsb-findings/01062050): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause) - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause) ## Analysis The pilot stated that he was maneuvering the airplane at low altitude to practice approaches at an unimproved airstrip. After passing over some trees in a northerly direction, the airplane began a rapid descent. The pilot applied full power in an effort to correct for the descent, but the engine power decreased. When the airplane was about 25 ft above ground level, the left wing struck a tree, and the airplane then impacted terrain in a slight left bank. The airplane slid along the ground for about 18 ft before impacting a berm, which caused the airplane to become airborne and rotate counterclockwise 180 degrees before coming to rest in a near-level pitch attitude. A Federal Aviation Administration airworthiness directive (AD) applicable to the airplane required that a placard with the following operating limitation be placed near the throttle: "DO NOT OPEN THROTTLE RAPIDLY – (IDLE TO FULL THROTTLE, 2 SECONDS MINIMUM.)" The AD was issued to prevent power interruption and acceleration hangup that could result from abrupt throttle movement. The airplane was in compliance with the AD. The pilot stated that, when he opened the throttle, he did so rapidly, faster than the 2-second requirement. It is likely that the pilot's rapid opening of the throttle interrupted the fuel supply to the engine, which resulted in a loss of engine power. ## Factual narrative On May 31, 2015, about 2000 Alaska daylight time, a tailwheel-equipped Piper PA-22 airplane, N2828P, sustained substantial damage after impacting terrain while maneuvering at low level about 17 miles southeast of Skwentna, Alaska. The student pilot and sole occupant received minor injuries. The airplane was registered to, and operated by, the pilot under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 as a personal cross-country flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 01, 2015, the pilot stated that he was maneuvering the airplane to "drag the runway" of an unimproved airstrip. After passing over some trees in a northerly direction, the airplane began a rapid descent. The pilot applied full power in an effort to correct for the descent, but the engine power decreased. About 25 feet above ground level (agl), the left wing struck a tree, and the airplane impacted terrain in a slight left bank. The airplane slid along the surface for about 18 feet before impacting a berm, which caused the airplane to become airborne and rotate counter clockwise 180 degrees before coming to rest in a near level pitch attitude. During a post-accident examination of the airplane, including maintenance records, it was discovered that Federal Aviation Administration (FAA) Airworthiness Directive (AD) 73-09-06 was applicable to Piper PA-22-150 airplanes with Lycoming O-320 series engines and Marvel Schebler Carburetors Model MA-4-SPA, part numbers 10-3678-11, 10-3678-12, and 10-3678-32. The accident airplane was equipped with a Lycoming O-320 engine and a Marvel Schebler Carburetor, model number MA-4SPA, P/N 10-3678-32, and the airplane was in compliance with the AD by having the required placard in place at the time of the accident. The AD states, in part: "To prevent power interruption and acceleration hangup resulting from abrupt throttle movement, accomplish the following: Attach the following operating limitation placard to the instrument panel near the throttle in full view of the pilot. Use 1/8 inch min. size lettering. 'DO NOT OPEN THROTTLE RAPIDLY – (IDLE TO FULL THROTTLE, 2 SECONDS MINIMUM)' The placard may be fabricated by the owner or operator." The pilot stated that when he advanced the throttle, he did so in a rapid motion, faster than the 2-second requirement. The closest weather reporting facility is Skwentna Airport, about 17 miles northwest of the accident site. At 1850, an aviation routine weather report (METAR) from the Skwentna Airport was reporting in part: winds from 290 degrees at 7 knots; visibility, 30 statute miles; sky condition, few clouds at 3500 feet, scattered at 20000 feet; temperature 77 degrees F; dewpoint 37 degrees F; barometric pressure 29.74inHG. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470) ## Aircraft - Registration: [N2828P](https://openairdocs.org/aircraft/N2828P), registered now, S/N 22-3121, built 1955 (OpenAirDocs) - Reported make and model: PIPER PA 22 - Registry model: [Piper PA-22](https://openairdocs.org/model/piper-pa-22) (registry code 7102202) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 22-3121 - Year built: 1955 - Airframe hours: 4082 - Engines: LYCOMING O-320 SERIES 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Levi S. Wood - Registered owner: Levi S. Wood - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 9, 2014 - Departed: SKW, SKWENTNA, AK - Destination: MRI, ANCHORAGE, AK - Equipment: Electronic flight bag or handheld device, Angle of attack indicator, ADS-B, Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 43; injuries: minor; student; medical: class 3, with waivers/limitations; seat: left; restraint: 3-point; flight hours: 55 total, 55 in this make and model, 14 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 7 knots - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 37 °F - Altimeter: 29.73 inHg - Observed at: PASW, 18 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 20150531013389A](https://openairdocs.org/incident/20150531013389A), May 31, 2015: Piper PA-22, Skwentna, AK, Destroyed. Accident occurred on may 31st, 2015 at approximately 8PM. The student pilot/pic had planned a goose bay, talkeetna, and Skwentna, Alaska solo cross-country… ## Other investigations on N2828P (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 ANC89LA079](https://openairdocs.org/ntsb/ANC89LA079), May 29, 1989: Piper PA-22 (N2828P), Anchorage, AK, substantial damage. Probable cause: A CRACK ON THE LEFT SIDE OF THE ENGINE CRANKCASE WHICH RESULTED IN A LOSS OF LUBRICATING OIL AND WHICH FORCED THE PILOT TO LAND ON A GRAVEL BAR WHICH RESULTED IN A NOSE OVER DURING LANDING. - [NTSB FTW66F0456](https://openairdocs.org/ntsb/FTW66F0456), Nov 22, 1965: Piper PA-22 (N2828P), Bandera, TX, substantial damage ## Docket (3 files) The files NTSB released with the investigation on July 30, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91283. 3.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40429918&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Memorandum for Record - Telephone Interview, Pilot (item 2, .PDF, 55 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40429919&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20-%20Telephone%20Interview,%20Pilot-Master.PDF - FAA Airworthiness Directive 73-09-06 (item 3, .PDF, 105 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40429920&FileExtension=.PDF&FileName=FAA%20Airworthiness%20Directive%2073-09-06-Master.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.