Accident Enstrom F28F N171HH,
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ASN Wikibase Occurrence # 354655
 
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Date:Monday 30 March 1998
Time:11:10 LT
Type:Silhouette image of generic EN28 model; specific model in this crash may look slightly different    
Enstrom F28F
Owner/operator:Herman's Helicopters
Registration: N171HH
MSN: 758
Year of manufacture:1988
Total airframe hrs:433 hours
Engine model:Lycoming HIO-360-F1AD
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Baker, OR -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Ferry/positioning
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot stated that he had lifted off from a road in open terrain so that a truck could get by. He stated that the lift-off was smooth. He noticed some shaking when he began forward flight. He increased the load on the rotor disk and the shaking became so violent that he couldn't see the ground. He dropped the collective and reached the ground. He said that the only way he could describe the situations was that 'it was like being in the spin cycle of a washing machine when all of the weight is on one side.' The helicopter had recently been imported to the US from Canada, and recertified with a US airworthiness certificate. The helicopter had been involved in a hard-landing accident in Japan on June 10, 1994. Damage to the aircraft at that time included the left skid, deformation of the fuselage and twisting of the tail boom. All three main-rotor blades had terrain impact The helicopter was later exported from Japan to Canada, where the importee stated that it was received in a repaired condition. No reference to the accident or its required repair was made in the Canadian maintenance or journey logs. No record was found for accomplishment of an inspection, as outlined in the Enstrom Maintenance Manual, for main rotor blade strike or hard landing inspections. The Safety Board materials laboratory inspected fragments from the steel tube pylon assembly, consisting of pieces of steel tubing that are welded to each other to form a frame structure for the helicopter. The steel tubes provide reinforcement for the four attachment points of the main transmission and other attachment points for the engine. Two of the steel tubes exhibited fatigue cracking, and completely separated during operation of the helicopter.

Probable Cause: Fatigue failure of the steel tubing pylon structure. Factors include inadequate inspection by maintenance personnel of damage after a previous accident.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: SEA98FA055
Status: Investigation completed
Duration: 1 year and 9 months
Download report: Final report

Sources:

NTSB SEA98FA055

Location

Revision history:

Date/timeContributorUpdates
11-Mar-2024 16:53 ASN Update Bot Added

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