Sikorsky S-76A N79K

Summary

On 22 September 1984 at about 15:30 local time, a Sikorsky S-76A registered N79K was involved in an accident near Unionville, Pennsylvania, United States. 14 people were on board. The aircraft was substantially damaged. No probable cause statement is available for this record.

Date

22 September 1984 at 15:30

Classification

Accident

Location

Unionville, Pennsylvania, United States

Coordinates

39.9003, -75.7404

Aircraft

Sikorsky S-76A

Registration

N79K

Category

Helicopter

Engines

2

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Coatesville → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

NYC84FA319

Injuries not recorded.

The NTSB has not published a probable cause for this record. No probable cause statement is present in the source data.

Nothing about the cause is stated here that is not in the source record.

Read the full NTSB narrative

ON APPROACH, ACFT YAWED RIGHT. PLT REDUCED POWER AND EXECUTED EMERG LNDG. BEFORE SHUTDOWN, IT WAS NOTED THE T/R WAS STATIONARY WHILE THE MAIN ROTOR CONTINUED TO TURN. INVESTIGATION REVEALED T/R DRIVE SHAFT HAD SEPARTED DUE TO THERMAL/MECHANICAL DAMAGE INCURRED BY CONTACT WITH ENGINE FIREWALL. FURTHER INVESTIGATION REVEALED THAT A FIREWALL MODIFICATION HAD BEEN DESIGNED WHICH INCLUDED A DOUBLER STRIP AT THE FWD AND AFT FIREWALL SECTION CONNECTION. PRESENCE OF DOUBLER WOULD DECREASE CLRNC BETWEEN FIREWALL AND T/R SHAFT. IT WAS FURTHER DETERMINED THAT, DURING INSTALLATION, THE FWD FIREWALL SECTION, TO WHICH THE DOUBLER IS ATTACHED, WAS MISPOSITIONED WITH RESULT THAT CLRNC WAS REDUCED TO NIL. COMPONENTS CAME INTO CONTACT DURING OPERATIONS.

Quoted verbatim from the NTSB record.