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Atlas / NTSB / CEN11LA370

NTSB CAROL · Event

Event CEN11LA370

2011-05-25 Lakeville, Minnesota, United States Serious 1 aircraft Status: Completed

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 ↗.

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.

Browse the full corpus — academia portal ↗