- Date
- July 31, 1998, 18:30 local (23:30 UTC)
- Place
- Grand Forks, ND
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Approach
- Aircraft
- N1001NBell M74L
- Weather
- Visual (VMC) · Day
- Status
- Completed · report January 28, 2000
- Report
- Approved by Office Director
- FAA report
- 19980731019139A
- Case key
- 43592
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 worn rotor clutch shoes, and subsequent loss of main rotor rpm.
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
The pilot refilled the hopper and was in the middle of a swath run when the engine rpm increased and the main rotor rpm decreased. The helicopter impacted the terrain during the forced landing and rolled over. A teardown of the transmission was performed. The inspection revealed that the clutch shoes were worn to the point that there was metal to metal contacted between the clutch shoe and the drum.
Factual narrative
On July 31, 1998, at 1830 central daylight time (cdt), a Bell M74-L (a modified Bell 47), N1001N, registered to Northland Helicopters, Inc., of Stacyville, North Dakota, was substantially damaged during a forced landing. The pilot reported a total loss of main rotor rom with an increase of engine rpm. The loss of rotor rpm occurred during a spray run. The commercial pilot was not injured. The 14 CFR Part 137 aerial application flight was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The flight departed near the accident site.
The pilot reported that he was operating the helicopter from a trailer near the accident site. He had just refilled the hopper and was in the middle of a swath run when the engine rpm increased and the main rotor rpm decreased. The helicopter impacted the terrain during the forced landing and rolled over.
A teardown of the transmission was performed which was overseen by an inspector from the Federal Aviation Administration Minneapolis, Minnesota, Flight Standards District Office. The inspection revealed that the clutch shoes were worn to the point that there was metal to metal contacted between the clutch shoe and the drum.
Aircraft
- Registration
- N1001N
- Reported as
- Bell M74L
- Category
- Helicopter
- Serial number
- 81-037
- Airframe hours
- 3,766
- Engine
- Lycoming VO-435, 265 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Registered owner
- Northland Helicopters, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- 100 hour · December 20, 1997 · 107 hours before
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
- 45
- Certificate
- Commercial
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Helicopter
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Center
- Flight hours
- 7,000 total · 250 in this make and model · 6,800 as pilot in command · 122 in the last 90 days · 15 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 140° at 9 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- 7,000 ft broken
- Temperature
- 77 °F, dew point 52 °F
- Altimeter
- 30.00 inHg
- Observed at
- GFK
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N1001N · 1
Matched to the same aircraft by N-number and date.