McDonnell Douglas 369E N34CT

Summary

On 25 June 2013 at about 13:50 local time, a McDonnell Douglas 369E registered N34CT, operated by Pinal County Sheriff's Office, was involved in an accident near Casa Grande, Arizona, United States. 3 people were on board and 3 had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 June 2013 at 13:50

Classification

Accident

Location

Casa Grande, Arizona, United States

Coordinates

32.8381, -111.7247

Aircraft

McDonnell Douglas 369E

Registration

N34CT

Category

Helicopter

Engines

1

Operator

Pinal County Sheriff's Office

Operating rule

Part 91: General Aviation

Purpose of flight

Flight Test

Phase of flight

Not recorded

Route

Casa Grande → Casa Grande

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR13LA290

3 people had minor injuries.

The total loss of engine power due to the ingestion of a foreign object and maintenance personnel's failure to remove shop rags before completing the installation of the air inlet barrier system.

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

Read the full NTSB narrative

Before the accident flight, maintenance personnel exchanged the helicopter's air inlet barrier filter system, during which the engine was removed from the helicopter. A preflight inspection was completed before departure of the postmaintenance check flight, and no discrepancies were noted. The engine start and pretakeoff checks were normal, and, after departure, the flight appeared to progress normally. About 1 to 2 minutes after completing an in-flight power check, the pilot heard a "distinct loud pop." Subsequently, the engine lost total power, and the pilot entered an autorotation. The helicopter landed hard, its right skid collapsed, and it rolled on its right side. A postaccident examination of the helicopter's engine air inlet found that cloth material had been ingested into the engine air intake. During further examinations, more cloth material was found in the engine in a sufficient quantity and location to block the airflow through the engine and cause it to flame out. The cloth material found in the engine was consistent with maintenance rags found in a box at the operator's hangar facility. It is likely that, during the maintenance of the helicopter's engine, maintenance personnel covered vulnerable areas of the engine with shop rags to prevent contamination, and, during the reinstallation of the engine, they did not remove all of the shop rags. The engine then ingested the rags during the postmaintenance test flight. Due to the installation of the engine air inlet barrier system, the shop rags would not have been visible during the preflight inspection nor could they have made it into the engine from the outside of the helicopter with the system in place. 

Quoted verbatim from the NTSB record.