Eurocopter Deutschland MBB BK-117 A4 N528SF

Summary

On 27 August 2002 at about 00:35 local time, a Eurocopter Deutschland MBB BK-117 A4 registered N528SF was involved in an incident near Bradenton, Florida, United States. 5 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

27 August 2002 at 00:35

Classification

Incident

Location

Bradenton, Florida, United States

Coordinates

27.4828, -82.5231

Aircraft

Eurocopter Deutschland MBB BK-117 A4

Registration

N528SF

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Naples → St. Petersburg

Aircraft damage

Minor

Weather

VMC

Light

Dusk

NTSB number

MIA02IA160

Nobody was injured.

Improper maintenance/installation of the No. 2 engine power turbine (PT) wheel assembly by company maintenance personnel, which resulted in deflection at the engine case axial midpoint and misalignment between the inlet housing and the rear bearing support housing (RBSH) which resulted in damage to the engine and an in-flight fire.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot said that while in cruise flight at an altitude of 1,000 feet, a speed of about 130 knots, and about 60 percent torque, without warning he heard a loud explosion from the right side of the helicopter, with simultaneous No. 2 engine fire and failure warning lights and indications, along with severe vibrations. He said that the helicopter yawed several times from left to right and he heard a "whopping" sound. He also said that at the same time the No. 1 engine torque meter needle moving rapidly from about the 9 to 3 or 4 o'clock positions on the gauge. The investigation revealed two of the power turbine blades and four rear bearing support housing (RBSH) failed in overload. The hub had been displaced from the engine centerline, and a deflection had occurred at the engine case axial midpoint, along with a misalignment of the inlet housing and the rear bearing support housing (RBSH). The resultant damage to the gas producer (GP) system, was consistent with an assembly error and mechanical failure having occurred by the loss of critical internal operating clearances and radial support for the rotors. Continued engine operation as the failure progressed led to compressor surge and the emergence of combustion gases from the No. 2 engine inlet, which ignited inlet cowling material. The No. 1 engine ingested smoke and combustion by-products from the engine cowling fire which caused a temporary stall condition.

Quoted verbatim from the NTSB record.