Kaman K-1200 N202WM

Summary

On 24 January 2023 at about 21:00 local time, a Kaman K-1200 registered N202WM, operated by Heliqwest International, Inc., was involved in an accident near Sweet Home, Oregon, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

24 January 2023 at 21:00

Classification

Accident

Location

Sweet Home, Oregon, United States

Coordinates

44.2467, -122.3678

Aircraft

Kaman K-1200

Registration

N202WM

Category

Helicopter

Year built

1995

Engines

1

Operator

Heliqwest International, Inc.

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

External Load

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR23LA097

Nobody was injured.

Improper installation of the hardware retaining the adjustment screw in the N2 topping governor lever and roller assembly, which resulted in a partial loss of engine power.

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

Read the full NTSB narrative

The accident occurred as the pilot was conducting a logging operation in a helicopter that had an overhauled engine recently installed. The helicopter sustained a loss of engine power when the pilot added power while laying a log into the log landing zone. Unable to maintain altitude, the pilot elected to make a forced landing onto open terrain. As the helicopter descended toward the open terrain, its landing gear impacted cut logs before the helicopter rolled down a hill and came to rest inverted. On the day before the accident, the pilot experienced what seemed to be a slower than normal governor response (governor lag) to an increase in power requirement. The company mechanic made engine adjustments and the pilot continued with the logging operations. On a later flight, the pilot heard “rushing air” while landing a log. He immediately returned to the service landing area and again consulted the mechanic. They confirmed the bleed band function, and the mechanic made an adjustment. They performed a ground run to confirm the adjustment did what they wanted it to and ended operations for the night. The engine was removed from the airframe and placed on a test stand following the accident. The power turbine governor (PTG) exhibited a random intermittency during functional testing, and a subsequent partial teardown revealed the locking feature of the adjusting screw of the N2 topping governor and roller assembly was not correctly clamped. A visual examination of the N2 topping governor lever and roller assembly revealed that the adjustment screw was not being retained by the locking tab and could easily be rotated. It was extended almost out of its threaded seat. The tab locking screw lockwire was undamaged and in its original location. Additionally, it was observed that the lock screw was free to turn within the lockwire hysteresis band, and no damage was noted on the threads of the screw and topping governor lever. The PTG was inspected and installed on the accident engine in April of 2020; the PTG time since overhaul was about 1,875 hours. The loose hardware retaining the adjustment screw in the N2 topping governor lever and roller assembly most likely caused an uncommanded rotation of the rockshaft and the subsequent opening of the bleed band. With the bleed band open air to the gas producer (GP) turbine was lost, resulting in a sudden loss of power. The loss of cooling air to the GP turbine also resulted in the thermal distress of the 2nd stage GP turbine blades.

Quoted verbatim from the NTSB record.