- Date
- March 16, 2010, 09:30 local (16:30 UTC)
- Place
- Parker, AZ
- Injuries
- 3 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N4282Eurocopter AS 350 B3
- Defining event
- Maneuvering-hover: Miscellaneous/other
- Weather
- Visual (VMC) · Day
- Status
- Completed · report July 1, 2010
- Report
- Approved by Office Director
- NTSB office
- Western Pacific Region
- Parties
- FAA FSDO
- FAA report
- 20100316032849A
- Case key
- 75545
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 mechanics' failure to account for all the tools following a maintenance procedure and the pilot's failure to perform a preflight check before a maintenance test flight.
Findings · 3
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
The pilot of the helicopter told the lead mechanic that the main rotor blade needed to be balanced. Two mechanics showed up on the morning of the accident and installed the balancing equipment. A test flight was flown. The two men performed the necessary work, which required a second adjustable wrench on the top of the rotor head to hold the bolt while the nut below was removed and later torqued back on. When the work was finished, the men gathered their tools. The pilot asked the lead mechanic if they had gathered all their tools and the mechanic replied "yes." The three men got on the helicopter for a test hover to check their work. As the main rotor speed reach 100 percent, the three occupants heard a "bang." As the helicopter hovered, the two mechanics thought the balancing equipment readings were worse than the first flight, and the vibrations in the aircraft had increased. The pilot landed the helicopter so that the mechanics could make additional adjustments. The mechanics discovered that they were missing the adjustable wrench that had been used on the top of the main rotor head. Postaccident examination revealed that one main rotor blade, the tail boom, and the lower vertical stabilizer had received damage from the unaccounted for wrench.
Factual narrative
The pilot of the helicopter told the lead mechanic that the main rotor blade needed to be balanced. Two mechanics showed up on the morning of the accident and installed the balancing equipment. A test flight was flown. The two men performed the necessary work, which required a second adjustable wrench on the top of the rotor head to hold the bolt while the nut below was removed and later torqued back on. When the work was finished, the men gathered their tools. The pilot asked the lead mechanic if they had gathered all their tools and the mechanic replied "yes." The three men got on the helicopter for a test hover to check their work. As the main rotor speed reach 100 percent, the three occupants heard a "bang." As the helicopter hovered, the two mechanics thought the balancing equipment readings were worse than the first flight, and the vibrations in the aircraft had increased. The pilot landed the helicopter so the mechanics could make additional adjustments. The mechanics discovered that they were missing the adjustable wrench that had been used on the top of the main rotor head. Post accident examination revealed that one main rotor blade, the tail boom, and the lower vertical stabilizer had received damage from the unaccounted for wrench.
Aircraft
- Registration
- N4282
- Reported as
- Eurocopter AS 350 B3
- Category
- Helicopter
- Serial number
- 4282
- Airframe hours
- 819
- Engine
- Turbomeca ARRIEL 2B1, 747 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Other work use · Part 91
- Operator
- Omniflight Helicopters inc.
- Registered owner
- Cfs Air LLC
- Airworthiness certificate
- Standard, Normal
- Last inspection
- AAIP · February 3, 2010
- Departed
- AZ47 · Parker, AZ
- Destination
- AZ47 · Parker, AZ
- Airport
- AZ47 · Lapaz Regional Hospital Helpt
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
- Age
- 52
- Injuries
- None
- Certificates
- Flight instructor, Commercial
- Instrument ratings
- Helicopter
- Medical
- Class 2, With waivers/limitations
- Last flight review
- March 21, 2009
- Seat
- Right
- Flight hours
- 3,900 total · 1,354 in this make and model · 28 in the last 90 days · 1 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 50° at 5 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 70 °F, dew point 39 °F
- Altimeter
- 30.30 inHg
- Observed at
- BLH
Docket · 1
The files NTSB released with the investigation on April 14, 2010, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.4 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.