Accident de Havilland Canada DHC-4A Caribou N702SC,
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Date:Thursday 30 January 1997
Time:00:10 LT
Type:Silhouette image of generic DHC4 model; specific model in this crash may look slightly different    
de Havilland Canada DHC-4A Caribou
Owner/operator:South Central Air
Registration: N702SC
MSN: 126
Total airframe hrs:13923 hours
Engine model:P&W R-2000
Fatalities:Fatalities: / Occupants: 2
Aircraft damage: Destroyed
Category:Accident
Location:Sparrevohn, AK -   United States of America
Phase: En route
Nature:Unknown
Departure airport:St Marys, AK (KSM)
Destination airport:Kenai, AK (ENA)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The CFR Part 135 cargo flight (flt) departed at night on an IFR flt with a load of mining equipment. Route of flt was over remote/mountainous terrain. About 2 hrs after takeoff, while cruising at 12,000' msl, the right engine (#2 eng) & propeller began to overspeed. The captain (capt) feathered the #2 eng & declared an emergency. He began to divert to an alternate destination, about 120 miles away in an area of lower terrain, but the aircraft (acft) would not maintain altitude (single eng service ceiling, as loaded, was about 8,700'). The capt increased power to the #1 eng, but it began to produce banging & coughing noises. The capt elected to perform an emergency landing at a nearby, remote, military airfield (A/F). The A/F was located in mountainous terrain & had a one-way, daylight only approach. The capt lowered the gear & flaps, & began a visual approach while attempting to keep the runway end identifier lights (REIL) in view. The acft encountered severe turbulence, & the capt applied full throttle to the #1 eng in an attempt to climb. The REIL disappeared from view, & the acft collided with snow covered terrain about 2 miles west of the A/F. Ground personnel at the A/F reported high winds & blowing snow with limited visibility. Postcrash exam of the #2 eng revealed a loss of the propeller control system hydraulic oil. Flt at 12,000' was conducted without crew oxygen. The crew had exceeded their maximum allowable duty day without adequate crew rest.

Probable Cause: loss of the right engine propeller control oil, which led to an overspeed of the right engine and propeller, and necessitated a shut-down of the right engine; and failure of the pilot to maintain adequate altitude/distance from terrain during visual approach for a precautionary landing at an alternate airport. Factors relating to the accident were: fluctuation of the left engine power, premature lowering of the airplane flaps, and an encounter with adverse weather conditions (including high winds, severe turbulence, and white-out conditions) during the approach.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ANC97FA024
Status: Investigation completed
Duration: 1 year and 3 months
Download report: Final report

Sources:

NTSB ANC97FA024

History of this aircraft

Other occurrences involving this aircraft
29 January 1997 N702SC Southcentral Air 1 3,5 km W of Sparrevohn Airport, AK (SVW) w/o
Loss of control

Location

Revision history:

Date/timeContributorUpdates
12-Mar-2024 20:58 ASN Update Bot Added

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