NTSB Identification: MIA87LA238.
The docket is stored on NTSB microfiche number 34904.
Nonscheduled 14 CFR
Accident occurred Wednesday, September 02, 1987 in ST THOMAS
Probable Cause Approval Date: 01/11/1989
Aircraft: AERO COMMANDER 680FL, registration: N111UA
Injuries: 7 Uninjured.

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

AFTER A LOSS OF HYD PRESSURE, THE RGT MAIN GEAR WOULD NOT FULLY EXTD WHEN THE PLT TRIED TO LOWER THE GEAR FOR LNDG. ALL ATMTS TO LOCK IT INTO PLACE WERE UNSUCCESSFUL. WHEN THE ACFT TOUCHED DOWN DRG THE LNDG, THE RGT MAIN GEAR COLLAPSED.THE ACFT SLID TO A STOP & THE OCCUPANTS WERE EVACUATED. AN INSPN OF THE RGT MAIN GEAR ASSY REVEALED THE HYD ACTUATING CYL HAD FAILED AT THE SNAP RING GROOVE & THE PNEUMATIC ACTUATING CYL HAD FAILED AT THE ROD END. BOTH FAILED FM OVERLOAD.THIS WAS THE 2ND OVERLOAD FAILURE OF THE HYD ACTUATING CYL IN 26 FLT HRS OF OPN. ACCORDING TO A MECHANIC, WHO WAS FAMILIAR WITH THE ACFT, THIS FAILURE WAS CONSISTENT WITH EXCESSIVE PRESSURE IN THE SYS DUE TO A PRESSURE RELIEF/UNLOADERVALVE MALFUNCTION.

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

HYDRAULIC SYSTEM,RELIEF VALVE..INOPERATIVE

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

LANDING GEAR,NORMAL RETRACTION/EXTENSION ASSEMBLY..OVERLOAD

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