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Atlas / NTSB / MKC87IA043

NTSB CAROL · Event

Event MKC87IA043

1987-01-23 SPRINGFIELD, Missouri, United States Airport · SGF None 1 aircraft Status: Completed

Registry · N120AM

FAA Aircraft Registry record.

Make / Model

AIRBUS HELICOPTERS INC AS350B3

Year of manufacture

2024

TCDS

H9EU · AIRBUS HELICOPTERS

Engine

SAFRAN ARRIEL 2D (952 hp)

Seats / Engines

7 seats · 1 engine

Last airworthiness date

20241220

ADS-B equipped

Yes — Mode-S A053BE

Registrant of record

AIR METHODS LLC

Source: FAA Aircraft Registry (releasable master file).

Aircraft involved

Factual narrative

THE PIC OF THIS AIR MIDWEST FLT 4408 SAID THAT, WHILE ON INITIAL CLIMB, POWER (NP) ON THE LEFT ENGINE DECAYED TO 60% AND WOULD NOT RECOVER. THE ENGINE WAS FEATHERED BY CONDITION LEVER BUT THE TORQUE ROSE TO 140% WHILE RETURNING FOR A LANDING, ACCORDING TO THE PIC. THE AIRCRAFT LANDED SAFELY. A POST-INCIDENT INVESTIGATION DISCLOSED THAT AN OIL LEAK HAD BEEN TRACED, THE DAY PRIOR TO THE INCIDENT, TO A FRACTURED PROPELLER CONTROL UNIT SOLENOID. THAT PART WAS REMOVED AND REPLACED AS A PRECAUTIONARY MEASURE. THE PLASTIC BLADE RETAINING RINGS INSIDE THE PROPELLER ASSY WERE DAMAGED DUE TO THE ENGINE OVERTORQUE AND SUBSEQUENT SHUTDOWN. A TEARDOWN OF THE PROPELLER CONTROL UNIT (PCU) SHOWED THAT THE BETA TUBE HAD NOT FAILED NOR WAS IT FREEWHEELING INSIDE THE PCU. A SPECTROGRAPHIC ANALYSIS OF OIL SAMPLES, DRAWN FROM FOUR SEPARATE SECTIONS OF THE ENGINE, TESTED SATIFACTORILY. AS SUCH, NO REASON COULD BE FOUND FOR THE DROP IN ENGINE POWER (NP) AND SUBSEQUENT OVERTORQUE. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1987_MKC87IA043.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. 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 ↗