Bell 47G 3B N147WT

Summary

On 30 March 2014 at about 16:30 local time, a Bell 47G 3B registered N147WT, operated by Lazy 7 Agricultural Services LLC, was involved in an accident near Oglesby, Texas, United States. 2 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

30 March 2014 at 16:30

Classification

Accident

Location

Oglesby, Texas, United States

Coordinates

31.3114, -97.3611

Aircraft

Bell 47G 3B

Registration

N147WT

Category

Helicopter

Year built

1964

Engines

1

Operator

Lazy 7 Agricultural Services LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Gatesville → Gatesville

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN14LA174

Nobody was injured.

Maintenance personnel’s failure to safety wire the throttle control adapter per maintenance instructions when the carburetor was replaced and to detect that the adapter was not safety wired during the annual inspection, which resulted in the throttle control disconnecting and subsequent loss of engine control.

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

Read the full NTSB narrative

The pilot reported that, during an en route climb in the helicopter, he increased the throttle and noticed a "slight resistance." Shortly after, the throttle freed up, but it was ineffective; there was no corresponding change in engine power when he moved the throttle control. Both the engine and rotor rpm were indicating in the green, but they began to decrease when he adjusted the collective. When he stopped moving the collective, the engine and rotor rpm increased rapidly and continued to accelerate. The pilot initiated an autorotation and cut off the fuel. The pilot then increased the collective, and the helicopter yawed left, touched down, and rolled over to the right, which resulted in the tailboom separating. A postaccident examination of the helicopter revealed that the throttle control adapter had disconnected from the serrated shaft on the carburetor. The retention screws on the throttle control adapter were not safety wired to the carburetor idle stop lever as required in the helicopter manufacturer's maintenance manual. A review of maintenance records revealed that the carburetor was removed and replaced about 1 1/2 years before the accident and that the helicopter's last annual inspection was conducted about 4 1/4 months before the accident.

Quoted verbatim from the NTSB record.