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Atlas / NTSB / NYC90FA156

NTSB CAROL · Event

Event NYC90FA156

1990-07-10 TETERBORO, New Jersey, United States Airport · TEB None 1 aircraft Status: Completed

Registry · N73LM

FAA Aircraft Registry record.

Make / Model

DIAMOND AIRCRAFT DA 40

Engine

LYCOMING I0360 SER (180 hp)

Seats / Engines

4 seats · 1 engine

Last airworthiness date

20020503

ADS-B equipped

Yes — Mode-S A9C9B8

Registrant of record

KRUEGER CARL R

Source: FAA Aircraft Registry (releasable master file).

Aircraft involved

Probable cause & findings

FAILED POWER TURBINE SHAFT. FACTORS IN THE ACCIDENT WERE CORROSION ON THE POWER TURBINE SHAFT AND INADEQUATE MANUFACTURER'S SERVICE BULLETINS.

Factual narrative

THE PILOT WAS HOVERING WHEN HE HEARD A WHINE IN THE ENGINE THAT INCREASED IN INTENSITY. HE SAW TORQUE FLUCTUATIONS, HEARD AN EXPLOSION, AND AUTOROTATED TO THE RAMP. INVESTIGATION SHOWED THE POWER TURBINE INNER SHAFT FAILED IN TORSION DUE TO CORROSION ON THE INNER SURFACE AND THIS ALLOWED THE THIRD STAGE TURBINE WHEEL TO GO INTO OVERSPEED AND FAIL. ALLISON ISSUED THREE SERVICE BULLETINS ON THE POWER TURBINE INNER SHAFT. NONE OF THEM USED CALENDAR TIME FOR COMPLIANCE, ONLY ENGINE TOTAL TIME. THE HELICOPTER WAS 11 YEARS OLD WITH 2146 HRS TT AIRFRAME AND ENGINE. THE FIRST SCHEDULED WORK ON THE POWER TURBINE OCCURS AT 3550 HRS. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1990_NYC90FA156.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.