Garlick TH-1L N465JR

Summary

On 5 November 1996 at about 22:00 local time, a Garlick TH-1L registered N465JR, operated by Kennedy, Robin, was involved in an accident near Leavenworth, Washington, United States. One person was on board and one died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

5 November 1996 at 22:00

Classification

Accident

Location

Leavenworth, Washington, United States

Coordinates

47.8094, -120.8592

Aircraft

Garlick TH-1L

Registration

N465JR

Category

Helicopter

Engines

1

Operator

Kennedy, Robin

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Aircraft damage

Destroyed

Weather

Unk

Light

Day

NTSB number

SEA97LA025

1 person died.

Fatigue failure of the vertical stabilizer spar cap and subsequent loss of the rotorcraft's vertical stabilizer. Factors include inadequate inspection or trouble-shooting of the aircraft tail cone and vertical stabilizer at and after the time sheet-metal skins were stop-drilled and rivets were replaced, and repetitive cycles associated with helicopter logging operations.

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

Read the full NTSB narrative

The pilot/operator, who had been utilizing the rotorcraft for heavy log lifting operations for the previous 18 months, was initiating a log lift cycle from a hover when the vertical stabilizer separated from the restricted category Garlick TH-1L. The rotorcraft subsequently descended out of control, impacting wooded, sloped terrain. Post-crash metallurgical examination discovered fatigue fractures emanating from a rivet hole within all five layers of the left side aluminum spar cap buildup for the vertical stabilizer. Additionally, fatigue cracking was observed within the tail boom skin near the vertical stabilizer and additional rivets were noted in both sides of the tail boom skin area. The tail boom skin crack was noted to have two separate stop holes drilled in its progression. Maintenance records showed no evidence of an inspection of the spar cap area or internal inspection of the tail cone or vertical fin at the time of installation of six blind rivets in the vertical fin, 18 months previous to the accident. No record was found recording the time of stop-drilling the skin crack progression. Examination of the riveted structure in the vicinity of the tailboom-to-vertical stabilizer junction revealed 30 blind rivets without paint on their exterior or interior ends on the left side of the vertical stabilizer, including seven that were directly adjacent to the separation point in the left cap of the stabilizer front spar. Four similar rivets were noted on the right side of the vertical stabilizer. Helicopter logging operations require repetitive high-stress/high-cycle operations.

Quoted verbatim from the NTSB record.