NTSB CAROL · Event
Event CEN11LA370
Registry · N96SH
FAA Aircraft Registry record.
Make / Model
BELL 47G-3B-1
Year of manufacture
1964 · 47 years old at event
TCDS
2H3 · SCOTT'S-BELL 47 INC
Engine
ALLISON 250-C10D (317 hp)
Seats / Engines
3 seats · 1 engine
Last airworthiness date
20000329
ADS-B equipped
Yes — Mode-S AD5B65
Registrant of record
VALIAIR LIMITED COMPANY TRUSTEE
Source: FAA Aircraft Registry (releasable master file).
Aircraft involved
Probable cause & findings
The loss of engine power due to a loose B-nut on the compressor discharge pressure bleed line.
Factual narrative
On May 25, 2011, about 1140 central daylight time, a Bell 47G-3B-1, N96SH, experienced a total loss of engine power while maneuvering near Lakeville, Minnesota. The pilot subsequently made a forced landing on a swamp near Lakeville, Minnesota. The certificated commercial pilot sustained serious injuries. The helicopter sustained substantial damage to the fuselage and tailboom when it impacted terrain during the forced landing. The helicopter was registered to and operated by Scotts Helicopter Services Inc under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed and no flight plan had been filed for the flight that originated from Flying Cloud Airport (FCM), Minneapolis, Minnesota. Examination of the engine (Rolls Royce Allison T63A700, serial number AE-400951) by a Federal Aviation Administration inspector from the Minneapolis Flight Standards District Office revealed that the Pc bleed line (from the governor to the fuel control) was leaking at the B-nut, which had come loose. The inspector stated that the operator had a spare engine at it facilities and that engine had torque lines painted onto the engine's fittings. The accident engine did not have torque lines painted onto its fittings. The inspector stated that there is no requirement to use torque lines and that the new engine maintenance manuals now discuss the use of torque lines. The time since the engine's last inspection was 59.4 hours. The pilot stated that the helicopter experienced a total loss of engine power while maneuvering during an aerial application operation. He performed a forced landing to a swamp, which resulted in substantial damage to the airframe. Examination of the engine revealed that the compressor discharge pressure bleed line between the governor and the fuel control was leaking at a loose B-nut. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).
- C Aircraft-Aircraft power plant-Engine bleed air system-(general)-Not specified - C
Verbatim from NTSB's published report. Source file
NTSB_2011_CEN11LA370.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (maintenance). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- Embry-Riddle Scholarly Commons 2026 · Journal article (IJAAA)
From Reactive to Predictive: A hybrid Trust-Mediated Adoption Framework for Data-Driven Maintenance in Distributed-Authority Aviation Environments
Modern aviation maintenance operates within increasingly data-intensive technological environments, yet the operational integration of predictive maintenance into routine decision-making remains incon…
- Semantic Scholar 2025 · Article (Applied Sciences)
Decision-Making Framework for Aviation Safety in Predictive Maintenance Strategies
The implementation of predictive maintenance (PM) in aviation presents unique challenges due to strict safety requirements, complex operational environments, and regulatory constraints.
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
Low-Resource Automatic Speech Recognition Domain Adaptation – A Case-Study in Aviation Maintenance
With timeliness and efficiency being critical in the aviation maintenance industry, the need has been growing for smart technological solutions that optimize and streamline the different underlying ta…
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
A New Trajectory in UAV Safety: Leveraging Reinforcement Learning for Distance Maintenance Under Wind Variations
In the field of aviation, safety is a critical cornerstone, and the operation of Unmanned Aerial Vehicle (UAV) systems is deeply connected with this principle.
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
Just Culture in Aviation: A Metaphorical Study on Aircraft Maintenance Students
Just Culture, a sub-dimension of safety culture, has been a prominent and debated topic in aviation safety in recent years.
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
Performance PRISM: A Comprehensive Framework For Performance Measurement In Aircraft Maintenance
Aircraft maintenance is governed by rigorous safety requirements and high operational complexity, demanding robust performance measurement frameworks to ensure optimal maintenance practices.
Browse the full corpus — academia portal ↗