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ASN Wikibase Occurrence # 134554
Last updated: 27 July 2017
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Date:11-JUL-1983
Time:16:23
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different
Aérospatiale AS 350D
Owner/operator:Era Helicopters, Inc.
Registration: N141EH
C/n / msn: 1460
Fatalities:Fatalities: 0 / Occupants: 4
Other fatalities:0
Airplane damage: Written off (damaged beyond repair)
Category:Accident
Location:Unalaska Airport, Dutch Harbor, Amaknak Island, Aleutian Islands, AK -   United States of America
Phase: Landing
Nature:Passenger
Departure airport:Unalaska Airport, Alaska (DUT/PADU)
Destination airport:Unalaska Airport, Alaska (DUT/PADU)
Investigating agency: National Transport Safety Bureau (NTSB)
Narrative:
APPROXIMATELY 2 MINUTES AFTER TAKEOFF, THE PILOT & PASSENGERS HEARD A LOUD MUFFLED BOOM FROM BEHIND THE FIREWALL, THEN THE ROTOR RPM BEGAN TO DECAY. THE PILOT ENTERED AN AUTOROTATION & SELECTED A LANDING AREA. HE NOTED THAT THE ENGINE WAS NOT DRIVING THE ROTOR SYSTEM, SO HE SHUT IT DOWN TO REDUCE THE POSSIBILITY OF FIRE WHILE LANDING. DURING AN EMERGENCY LANDING ON SLOPING, MOUNTAINOUS TERRAIN, THE HELICOPTER ROLLED OVER, AND SUBSEQUENTLY, IT CAME TO REST IN A RAVINE AT THE BOTTOM OF THE SLOPE.

A TEARDOWN OF THE ENG REVEALED THAT THE #3 BEARING, PN 4-301-051-02, HAD FAILED & THAT THE OIL JET FOR THE BEARING WAS CLOGGED. REPORTEDLY, MAINTENANCE PERSONNEL WERE AWARE THAT A DIFFERENTIAL PRESSURE CHECK, TO DETECT CLOGGING TO THE #2 & #3 PACKAGED OIL JETS, WAS 7 TO 8 PSI. THIS WAS 2 TO 3 PSI TOO HIGH & INDICATED CLOGGING OF THE OIL JETS. (THIS PROCEDURE WAS OUTLINED IN LYCOMING SVC BULLETIN LTS101A-17-0014). HOWEVER, THE DISCREPANCY WAS NOT ENTERED IN THE ENG MAINTENANCE LOGS.

Sources:

1, NTSB: http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001214X43555&key=1
2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=141EH
3. http://www.helis.com/database/cn/34963/
4. http://www.griffin-helicopters.co.uk/accidentdetails.aspx?accidentkey=11583
5. http://en.wikipedia.org/wiki/Unalaska_Airport


Revision history:

Date/timeContributorUpdates
27-Jun-2014 19:16 Dr. John Smith Updated [Location, Nature, Departure airport, Destination airport, Source, Narrative]
21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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