# NTSB ANC96LA115: de Havilland DHC-4, N800NC, New Stuyahok, AK, August 2, 1996

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 2, 1996, 11:00 local (19:00 UTC)
- Place: New Stuyahok, AK
- Coordinates: 59.489261, -157.29074 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=59.4893&lon=-157.2907&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report February 18, 1997
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 2872
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC96LA115
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2872/pdf
- Page: https://openairdocs.org/ntsb/ANC96LA115

## Probable cause

The collapse of the nosegear precipitated by the failure of the hydraulic nosegear drag strut locking actuator.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Nose gear collapsed, landing - roll
  - landing gear,nose gear - unlocked
  - landing gear,nose gear - collapsed
  - hydraulic system,actuator - failure (cause)

## Analysis

The airplane's nosegear collapsed during a landing roll on a gravel airstrip.  Subsequent examination of the nosegear locking mechanism disclosed a failed hydraulic drag strut locking actuator.

## Factual narrative

On August 2, 1996, about 1100 Alaska daylight time, a deHavilland DHC-4 airplane, N800NC, registered to and operated by Greatland Air Cargo, sustained substantial damage while landing at the New Stuyahok airstrip, New Stuyahok, Alaska. The commercial certificated captain and first officer were not injured. The 14 CFR Part 135 cargo flight operated in visual meteorological conditions.

During a telephone interview with the NTSB investigator-in-charge on August 5, the captain related that during the landing roll at New Stuyahok, the nose gear suddenly collapsed. The captain said the landing was normal and uneventful until the nosegear collapsed. He also said that the green, gear down and locked light, was appropriately illuminated, and that he was uncertain why the nosegear collapsed.

The airplane was returned to its maintenance base and repaired.  According to the pilot, the nose gear hydraulic drag strut actuator malfunctioned, and failed to remain in the down locked position.  He said the part was changed, and the nosegear operated properly.  He also indicated that the drag strut actuator service life is "on condition."  The failed part, part number 5460-3, had approximately 1400 service hours at the time of failure.  The pilot, who is also a certificated aviation mechanic, believes that additional inspections of the drag strut and associated hoses are warranted.

## Aircraft

- Registration: [N800NC](https://openairdocs.org/deregistered/N800NC-2001-09-10), registration cancelled 2001-09-10, S/N 98 (OpenAirDocs)
- Reported make and model: de Havilland DHC-4
- Registry model: [Dehavilland CARIBOU DHC-4A](https://openairdocs.org/model/dehavilland-caribou-dhc-4a) (registry code 2800304) (OpenAirDocs)
- Category: Airplane
- Serial number: 98
- Airframe hours: 14638
- Engines: P&W R2000-7M2 1450 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Greatland Air Cargo
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, August 1, 1996, 3 hours before
- Departed: ANC, ANCHORAGE, AK
- Destination: KNW
- Flight plan: Company VFR
- Airport: KNW, New Stuyahok

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 49; commercial; airplane ratings: single-engine sea, multi-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 15,670 total, 850 in this make and model, 15,670 as pilot in command, 334 in the last 90 days, 108 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 10 knots
- Visibility: 20 statute miles
- Lowest ceiling: 1,000 ft broken
- Temperature: 61 °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 19960802025999A](https://openairdocs.org/incident/19960802025999A), Aug 2, 1996: Dhav DHC4A, New Stuyahok, AK, Substantial damage. Nose gear collapsed landing. Hydraulic strut actuator failed remain in downlocked position. Better gear checks.

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.

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