NTSB Identification: CHI83IA054
14 CFR Part 91: General Aviation
Incident occurred Friday, December 10, 1982 in OVER FARGO, ND
Probable Cause Approval Date: 12/10/1983
Aircraft: GATES LEAR JET 35A, registration: N1500E
Injuries: 3 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

WHILE LEVEL AT FL370 OVER FARGO, ND, THE CREW HEARD A LOUD BANG IN THE ENGINE AREA AND THE AIRCRAFT EXPERIENCED A SUDDEN LOSS OF CABIN PRESSURE. AT THE SAME TIME, THE CREW NOTICED THAT THEY HAD LOST POWER ON THE #2 ENGINE. AFTER SECURING THE ENGINE AND REGAINING CONTROL OF THE CABIN PRESSURIZATION, THE FLIGHT WAS CONTINUED TO MILWAUKEE, WI, WITHOUT FURTHER INCIDENT. EXAMINATION REVEALED TWO JAGGED HOLES IN THE ENGINE COWL AND ONE THROUGH THE AFT FUSELAGE. DETAILED EXAMINATION OF THE ENGINE REVEALED THAT IT HAD EXPERIENCED A SEGMENT SEPARATION OF THE 2ND STAGE LOW PRESSURE TURBINE DISC. THE CHUNK FAILURE WAS A RESULT OF IMPROPER MACHINING OF THE FORWARD SIDE WEB AREA OF THE DISC. THE PRESSURIZATION DROP OCCURRED WHEN SEPARATION DISC FRAGMENTS STRUCK AND DISABLED THE 3 WAY BLEED VALVE.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

TURBINE ASSEMBLY,TURBINE WHEEL..DISINTEGRATED

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

INADEQUATE QUALITY CONTROL..MANUFACTURER

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