NTSB Identification: ANC93FA070.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Friday, May 28, 1993 in ANCHORAGE, AK
Probable Cause Approval Date: 11/10/1994
Aircraft: CESSNA 320, registration: N4198T
Injuries: 1 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

THE PILOT SAID THAT DURING FLIGHT, HE ENCOUNTERED AN OVERVOLTAGE CONDITION & TURNED OFF THE ELECTRICAL MASTER SWITCH. HE NOTED THAT THE VHF RADIO CIRCUIT BREAKER HAD TRIPPED & THE TURN & BANK INDICATOR SMOKED. HE SAID THAT ABOUT 10 MILES FROM THE AIRPORT, HE TURNED THE MASTER SWITH BACK ON & TRIED TO RESET THE CIRCUIT BREAKER, BUT AGAIN HE NOTED SMOKE IN THE COCKPIT. HE SAID THE LANDING GEAR EXTENDED VERY FAST & HARD, BUT IT DID NOT LOCK. WHEN HE ATTEMPTED TO FOLLOW THE EMERGENCY GEAR EXTENSION PROCEDURE, THE CRANK DID NOT WORK. THE MAIN GEAR COLLAPSED DURING LANDING. AN EXAM OF THE ELECTRICAL SYSTEM DISCLOSED A CHARRED & EXPANDED BATTERY. THE DOWN LIMIT SWITCH FOR THE LANDING GEAR MOTOR HAD BROKEN FROM ITS MOUNT BY THE UPPER BELL CRANK TRAVELING BEYOND THE DOWN LIMIT; A TEARDOWN OF THE LANDING GEAR ACTUATOR ASSEMBLY DISCLOSED EVIDENCE OF OVERTRAVEL. THE ALTERNATORS, VOLTAGE REGULATORS & OVER VOLTAGE RELAY ALL TESTED WITHIN ALLOWABLE LIMITS.

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

AN UNDETERMINED FAILURE THAT RESULTED IN AN OVERVOLTAGE CONDITION OF THE ELECTRICAL SYSTEM, OVERHEATING OF THE BATTERY, OVERDRIVE (OVERTORQUE) OF THE LANDING GEAR EXTENSION SYSTEM, A DISCONNECT OF THE EMERGENCY EXTENSION SYSTEM, AND A SUSBSEQUENT COLLAPSE OF THE MAIN GEAR WHEN IT COULD NOT BE LOCKED IN THE EXTENDED POSITION.

Full narrative available

Index for May1993 | Index of months