# NTSB ANC11TA079: Dehavilland DHC-2 MK. I(L20A), N723DR, Northway, AK, August 3, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: August 3, 2011, 09:50 local (17:50 UTC) - Place: Northway, AK - Coordinates: 64.900886, -157.689743 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=64.9009&lon=-157.6897&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report November 3, 2011 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA - Anchorage FSDO - NTSB case key (mKey): 81537 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC11TA079 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81537/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81537 - Page: https://openairdocs.org/ntsb/ANC11TA079 ## Probable cause The pilot's failure to identify unsuitable terrain for landing and subsequent contact with a dirt mound, resulting in the separation of the tailwheel from the airframe. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Dehavilland DHC-2 MK. I(L20A), 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=2808002), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) - [Object/animal/substance: hidden/submerged object](https://openairdocs.org/ntsb-findings/03022052): Environmental issues › Physical environment · Effect on equipment; cases with it: [Dehavilland DHC-2 MK. I(L20A), 1 case](https://openairdocs.org/ntsb-findings/03022052/cases.md?model=2808002), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/03022052/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Dehavilland DHC-2 MK. I(L20A), 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=2808002), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Abnormal runway contact](https://openairdocs.org/ntsb-events/090); cases with it: [Dehavilland DHC-2 MK. I(L20A), 1 case](https://openairdocs.org/ntsb-events/090/sequence.md?model=2808002), [All aircraft, 1,506 cases](https://openairdocs.org/ntsb-events/090/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Dehavilland DHC-2 MK. I(L20A), 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=2808002), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The pilot stated that during the landing roll he noticed a problem with the tailwheel. After he unloaded the passengers, he realized that the tailwheel casting had broken and the tailwheel spindle and fork had separated from the airframe. He inspected the landing area and noticed that he had hit a 4-inch bank of dirt that he had not seen in the grass. The airplane sustained substantial damage to the aft fuselage bulkhead. ## Factual narrative On August 3, 2011, about 0950 Alaska daylight time, a deHavilland DHC-2 airplane, N723DR, sustained substantial damage during an off-airport landing approximately 40 miles south of Northway, Alaska. The airplane was registered to and operated by Copper Valley Air Service, LLC, Glennallen, Alaska, under the provisions of 14 Code of Federal Regulations (CFR) Part 135 as an on-demand air taxi flight, under contract to the U.S. National Parks Service (NPS). The pilot and four passengers were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The public use flight originated at the Gulkana Airport, Glennallen, Alaska about 0830. The purpose of the flight was to transport NPS employees to a remote site to take water samples and do a site survey. In a written statement to the National Transportation Safety Board (NTSB), the pilot stated that during the landing, as the airplane was coming to a stop, he noticed a problem with the tailwheel. After he unloaded the passengers, he realized that the tailwheel casting had broken, and the tailwheel spindle and fork had separated from the airframe. He inspected the landing area, and noticed that he had hit a small, 4-inch, bank of dirt in the grass that he had not seen. A postaccident examination of the airplane by a Federal Aviation Administration (FAA) airworthiness inspector discovered substantial damage the aft fuselage bulkhead. ## Aircraft - Registration: [N723DR](https://openairdocs.org/aircraft/N723DR), registered now, S/N 1546, built 1964 (OpenAirDocs) - Reported make and model: DEHAVILLAND DHC-2 MK. I(L20A) - Registry model: [Dehavilland DHC-2 MK. I(L20A)](https://openairdocs.org/model/dehavilland-dhc-2-mk-i-l20a) (registry code 2808002) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1546 - Airframe hours: 15651 - Engines: P&W R-985 SERIES 450 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Copper Valley Air Service LLC - Registered owner: Copper Valley Air Service LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 4, 2011 - Departed: PAGK, Glennallen, AK - Destination: Northway, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review June 3, 2011; seat: left; flight hours: 8,800 total, 1,800 in this make and model, 8,100 as pilot in command, 165 in the last 90 days, 60 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Temperature: 64 °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 20110803018019A](https://openairdocs.org/incident/20110803018019A), Aug 3, 2011: Dehavilland DHC-2 MK. I(L20A), Glennallen, AK, Substantial damage. Pilot told the ASI, he performed a two point landing at a remote, off-airport strip called "Snag River Camp" with 4 passengers from the national park service… ## Docket (1 files) The files NTSB released with the investigation on October 3, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81537. 434 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 434 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40354333&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.