Robinson R44 N444WT

Summary

On 19 May 2012 at about 20:40 local time, a Robinson R44 registered N444WT, operated by Timberview Helicopters, was involved in an accident near Destin, Florida, United States. 3 people were 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

19 May 2012 at 20:40

Classification

Accident

Location

Destin, Florida, United States

Nearest airport

Destin (KDTS)

Coordinates

30.3999, -86.4908

Aircraft

Robinson R44

Registration

N444WT

Category

Helicopter

Engines

1

Operator

Timberview Helicopters

Operating rule

Part 91: General Aviation

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Destin → Destin

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA12LA346

Nobody was injured.

The partial loss of engine power due to a stuck (open) exhaust valve in the No. 5 cylinder. Contributing to the accident was the operator’s failure to follow the engine manufacturer’s directives concerning cooling of the engine after flight.

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

Read the full NTSB narrative

The helicopter reached about 200 feet above ground level in the initial climb when the pilot noticed that the engine needle in the dual tachometer (engine/main rotor rpm) had "spiked" and then remained "at the top of the gauge." The pilot turned the helicopter around to return to the airport, and, during the turn, the low rotor rpm warning alarm sounded. The pilot responded by lowering the collective control and increasing throttle but then determined that an airport landing could not be completed because the helicopter had already lost altitude. The pilot selected a forced landing area in a sand pit and responded to another low rotor rpm alarm by again lowering the collective. She attempted to cushion the landing with the available rotor rpm, but the helicopter landed hard, and the main rotor blades severed the tailboom. Examination of the helicopter revealed that the engine had a stuck (open) number 5 exhaust valve caused by buildup of oil carbon deposits. This is an issue with the Robinson Helicopters if the engine is not cooled down properly after flight. Air tour operations seem to be prone to carbon buildup mainly due to quick multiple shutdowns. The operator has established a postflight cool down procedure to prevent further problems. On January 19, 1988, Textron Lycoming published Service Letter No. L197A, Recommendations to Avoid Valve Sticking. The guidance offered included, "Rapid engine cool down from low power altitude changes, low power landing approach and/or engine shutdown too soon after landing or ground runs should be avoided."

Quoted verbatim from the NTSB record.