Hiller UH-12E N161HA

Summary

On 20 November 1993 at about 16:45 local time, a Hiller UH-12E registered N161HA, operated by R and B Helicopters Inc., was involved in an accident near Salinas, California, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 November 1993 at 16:45

Classification

Accident

Location

Salinas, California, United States

Coordinates

36.6708, -121.6108

Aircraft

Hiller UH-12E

Registration

N161HA

Category

Helicopter

Engines

1

Operator

R and B Helicopters Inc.

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX94LA054

1 person had minor injuries.

a fatigue failure of the torsion-tension bar pin due to fretting corrosion. A factor in this accident was an inadequate quality of material utilized in the manufacture of the pin.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

DURING A SWATH RUN TO APPLY A MIXTURE OF PESTICIDES, THE PILOT HEARD A LOUD 'POP'. THE HELICOPTER'S COLLECTIVE CONTROL BEGAN TO OSCILLATE AND THE AIRCRAFT EXPERIENCED A SEVERE VIBRATION. THE HELICOPTER ALSO BEGAN TO OSCILLATE AND THE PILOT SLOWED TO ABOUT 15 KNOTS AND ATTEMPTED TO LAND. A SPRAY BOOM ATTACHED TO THE HELICOPTER CONTACTED THE GROUND AND THE HELICOPTER ROLLED ON ITS LEFT SIDE. EXAMINATION REVEALED THE PRESENCE OF FRETTING CORROSION AND A FATIGUE FAILURE OF THE TENSION-TORSION BAR PIN, INTO WHICH THE MAIN ROTOR BLADE DRAG BRACE IS ATTACHED. A SECOND TENSION-TORSION PIN FROM A SISTER HELICOPTER WAS DISCOVERED TO ALSO HAVE CORROSION AND A FATIGUE CRACK. PINS FAILED AT 369.5 HOURS AND 489.4 HOURS RESPECTIVELY. THE RETIREMENT LIFE OF THE PIN IS 643 HOURS.

Quoted verbatim from the NTSB record.