NTSB Identification: LAX91LA038.
The docket is stored on NTSB microfiche number 43990.
Accident occurred Saturday, November 24, 1990 in PHOENIX, AZ
Probable Cause Approval Date: 04/13/1992
Aircraft: Aerostar S-77A, registration: N3605T
Injuries: 2 Serious,5 Minor.

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

WHILE BOARDING PSNL FOR A LAUNCH, THE BALLOON (BLN) WAS INFLATED & TETHERED TO A VEHICLE WITH A QUICK RELEASE LINE. WINDS AT THE TIME WERE ESTD TO BE ABT 7 KTS & SLIGHTLY GUSTY. DRG THE LAUNCH, THE PLT ADDED HEAT TO TAKEOFF & SIGNALED FOR A RELEASE, BUT THE QUICK RELEASE LINE FAILED TO RELEASE. THE BLN SETTLED TO THE GND & 'BOBBED' UP & DWN 2 TIMES. THE PLT RPRTD THAT AT THE HEIGHT OF A BOUNCE (ABT 6 TO 10 FT), ALL 28 OF THE ADVANCED FIBER TECHNOLOGY (AFT) KEVLAR SUSPENSION CABLES FAILED. THE BASKET FELL TO THE GND & THE ENVELOPE ROSE TO ABT 500 TO 700 FT, THOUGH THE RED LINE STAYED ATTACHED TO THE BASKET & OPENED THE DEFLATION PORT; 2 OF THE 7 OCCUPANTS RCVD SERIOUS INJURIES. AN EXAM REVEALED STRENGTH DEGRADATION OF THE KEVLAR CABLES DUE TO HEAT EXPOSURE. THE BLN HAD 240 HRS OF FLT TIME. STRENGTH LOSS WAS FND IN SOME AFT/KEVLAR CABLES OF OTHER BLNS. ON 11/28/90, AEROSTAR INTL SVC BULLETIN #129 WAS ISSUED TO RETROFIT ALL S-66A & S-77A BNS WITH STEEL CABLES.

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

STRENGTH DEGRADATION OF THE KEVLAR SUSPENSION CABLES, DUE TO PREVIOUS HEAT DAMAGE. FACTORS RELATED TO THE ACCIDENT WERE: FAILURE OF THE QUICK RELEASE LINE TO RELEASE, AND SUSCEPTIBILITY OF KEVLAR SUSPENSION CABLES TO HEAT.

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