Sikorsky S-58E N70709

Summary

On 13 February 1984 at about 21:30 local time, a Sikorsky S-58E registered N70709 was involved in an accident near Morgan City, Louisiana, United States. 5 people were on board and one was seriously injured, 3 had minor injuries. The aircraft was substantially damaged. No probable cause statement is available for this record.

Date

13 February 1984 at 21:30

Classification

Accident

Location

Morgan City, Louisiana, United States

Coordinates

29.7290, -91.1291

Aircraft

Sikorsky S-58E

Registration

N70709

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW84LA136

1 person was seriously injured.

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

THE HELICOPTER WAS HOVERING ABOVE TREES AT ABOUT 100 FT AGL WHEN THE TAIL ROTOR CHIP DETECTOR LGT FLICKERED SVRL TIMES, THEN ILLUMINATED STEADILY. THIS WAS FOLLOWED BY A LOUD GRINDING NOISE FROM THE TAIL AREA & THE ACFT YAWED TO THE RIGHT. THE ACFT ENTERED AN AUTOROTATION AFTER MAKING 3 TURNS TO THE RIGHT. IT DESCENDED INTO THE TREES AT WHICH TIME THE MAIN ROTOR BLADES WERE BROKEN OFF. AN EXAM OF THE INTERMEDIATE TAIL ROTOR GEAR BOX DISCLOSED THAT 6 TEETH IN THE INPUT BEVEL PINION GEAR, PN S1635-64114, HAD FAILED IN THE ROOT AREA. A METALLURGICAL EXAM DETERMINED THAT THE FAILURE ZONE HAD FATIGUE INDICATIONS. CRACKS WERE FOUND IN OTHER AREAS OF THE GEAR BOX. SIKORSKY ENGINEERS DETERMINED THAT THE GEAR BOX HAD BEEN SUBJECTED TO HEAVY LOADS. THE GEAR BOX HAD BEEN LAST OPENED IN 1968. ONE GEAR WAS NOT A SIKORSKY PRODUCT.

Quoted verbatim from the NTSB record.