- Date
- December 16, 2004, 16:20 local (22:20 UTC)
- Place
- Rockford, AL
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N51AGBell UH-1H
- Weather
- Visual (VMC)
- Status
- Completed · report September 13, 2005
- Report
- Approved by Office Director
- Parties
- Birmingham FSDO-09
- Case key
- 60748
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The pilot's failure to maintain adequate obstacle clearance, which resulted in an in-flight collision with a tree.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
According to the pilot, during a turn while applying fertilizer over pine trees he heard a "loud bang"; at the same time he lost tail rotor authority. The pilot attempted to level the helicopter and settled into the trees. Post accident examination reveal the helicopter was upright and on its skids. Flight control continuity was established with the cyclic and the collective controls. Examination of the tail rotor blades revealed leading edge damage on both blades. Examination of the helicopter revealed the lower fuselage was buckled and the tail rotor rear housing of the tail rotor gearbox transmission was broken and cracked. The tail rotor assembly was examined and revealed that the fracture features on the case assembly indicated an overload event. The wear patterns on the teeth of the bevel gears within the gearbox indicated that they were forced apart. There were no indications of any pre-exiting conditions on the components examined that would suggest a failure before the tail rotor strike.
Factual narrative
On December 16, 2004, at 1620 central standard time, a Bell UH-1, N51AG, registered to and operated by AG Rotors, collided with trees during a spraying operation five miles west of Rockford, Alabama. The agricultural flight was operated under the provisions of Title 14 Part 137 with no flight plan filed. Visual meteorological conditions prevailed at the time of the accident. The pilot was not injured and the helicopter sustained substantial damage. The flight departed from a field site located in the vicinity of Rockford, Alabama, on December 16, 2004, at 1600.
According to the pilot, during a turn while applying fertilizer over pine trees he heard a "loud bang"; at the same time he lost tail rotor authority. The pilot attempted to level the helicopter and settled into the trees.
Post accident examination reveal the helicopter was upright and on its skids. Flight control continuity was established with the cyclic and the collective controls. Examination of the tail rotor blades revealed leading edge damage on both blades. Examination of the helicopter revealed the lower fuselage was buckled and the tail rotor rear housing of the tail rotor gearbox transmission was broken and cracked. The tail rotor assembly was examined and revealed that the fracture features on the case assembly revealed an overload event. The wear patterns on the teeth of the bevel gears within the gearbox showed that they were forced apart. There was no evident of any pre-exiting condition on the components examined that would suggest a failure before the tail rotor strike.
Aircraft
- Registration
- N51AG
- Reported as
- Bell UH-1H
- Category
- Helicopter
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Operator
- AGRotors Inc.
- Departed
- Rockford, AL
- Destination
- Rockford, AL
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Injuries
- None
Weather
- Conditions
- Visual (VMC)
- Wind
- 0° at 0 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 46 °F, dew point 45 °F
- Altimeter
- 30.47 inHg
- Observed at
- ALX