Aviation Accident Summaries

Aviation Accident Summary MIA04LA123

Panama City, FL, USA

Aircraft #1

N107PH

BELL 206B3

Analysis

The pilot stated he flew out from Panama City-Bay County International Airport to survey a boat located on Deer Point Lake, approximately 8 miles northeast of the airport. With an altitude of about 50 feet and a forward airspeed around 35 to 40 mph he entered a circling maneuver. While flying upwind he reduced engine RPM, and as he turned downwind, he pulled up on the collective, but felt the helicopter sinking instead of climbing. He then looked at the engine instruments and saw the rotor RPM going below 85%. Immediately, he pushed the collective down, but was unable to regain RPM. He deployed emergency floats about 10 feet above the water. The helicopter hit the water "hard" in about 4 feet of water and then rolled onto its right side, due to the right flotation bag being torn off upon impacting the water. The FAA inspector who responded to the accident stated, upon inspection of the helicopter, after recovery, it was found that a pneumatic tubing line had backed off the governor and caused the engine to go to minimum RPM. The governor was last installed 500 hours before the accident and showed signs of a torque seal on the B-nut. The pneumatic line that backed off the fitting is located on the backside of the governor and is hard to see and check for proper torque during routine maintenance.

Factual Information

On August 24, 2004, about 1720 central daylight time, a Bell 206B, N107PH, registered to and operated by Heliworks Inc., as a Title 14 CFR Part 135 on demand air taxi flight, crashed into Deer Point Lake, Panama City, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The commercial-rated pilot and two passengers received no injuries, and the helicopter incurred substantial damage. The flight originated from Panama City-Bay County International Airport, Panama City, Florida, earlier that day, about 1700. The pilot stated he flew out from Panama City-Bay County International Airport to survey a boat located on Deer Point Lake, approximately 8 miles northeast of the airport. With an altitude of about 50 feet and a forward airspeed around 35 to 40 mph he entered a circling maneuver. While flying upwind he reduced engine RPM, and as he turned downwind, he pulled up on the collective, but felt the helicopter sinking instead of climbing. He then looked at the engine instruments and saw the rotor RPM going below 85%. Immediately, he pushed the collective down, but was unable to regain RPM. He deployed emergency floats about 10 feet above the water. The helicopter hit the water "hard" in about 4 feet of water and then rolled onto its right side, due to the right flotation bag being torn off upon impacting the water. The FAA inspector who responded to the accident stated, upon inspection of the helicopter, after recovery, it was found that a pneumatic tubing line had backed off the governor and caused the engine to go to minimum RPM. The governor was last installed 500 hours before the accident and showed signs of a torque seal on the B-nut. He stated the pneumatic line that backed off the fitting is located on the backside of the governor and is hard to see and check for proper torque during routine maintenance. The following are excerpts taken from Rolls-Royce 250-C20 series Operation and Maintenance list of Warnings: Proper tightening of engine tubing is critical to flight safety. Correct torque values must be used at all times. Excessive torque on pneumatic sensing system connections results in cracking of the flare or adjacent tube area in contact with the ferrule. This produces an air leak, which can cause engine flame out, power loss, or overspeed. Tubing B-nuts used in installations exposed to a high degree of vibration and pressure surges are subject to torque relaxation when improperly tightened. Air leaks in the fuel system or the pneumatic sensing system can cause flameouts, power loss, or overspeed.

Probable Cause and Findings

Inadequate maintenance inspection resulting in the partial loss of engine power due to a loose pneumatic line on the governor and ditching of the helicopter.

 

Source: NTSB Aviation Accident Database

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