Israel 1124 N4MH

Summary

On 18 March 2019 at about 20:31 local time, a Israel 1124 registered N4MH, operated by Sundance Airport FBO LLC, was involved in an accident near Yukon, Oklahoma, United States. 2 people were on board and 2 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

18 March 2019 at 20:31

Classification

Accident

Location

Yukon, Oklahoma, United States

Nearest airport

Sundance Airport (HSD)

Coordinates

35.6044, -97.7056

Aircraft

Israel 1124

Registration

N4MH

Category

Airplane

Year built

1978

Engines

2

Operator

Sundance Airport FBO LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Panama City → Oklahoma City

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

CEN19FA104

2 people died.

The airplane’s unairworthy thrust reverser (T/R) system due to inadequate maintenance that resulted in an asymmetric T/R deployment during an approach to the airport and the subsequent loss of airplane control.

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

Read the full NTSB narrative

The two commercial pilots were conducting a personal, cross-country flight. A video surveillance camera at the airport captured their airplane’s approach. Review of the video revealed that, as the airplane approached the approach end of the landing runway, it began to climb, rolled left, became inverted, and then impacted terrain. The left thrust reverser (T/R) was found open and unlatched at the accident site. An asymmetric deployment of the left T/R would have resulted in a left roll/yaw. The lack of an airworthy and operable cockpit voice recorder, which was required for the flight, precluded identifying which pilot was performing pilot flying duties, as well as other crew actions and background noises, that would have facilitated the investigation. Postaccident examination of the airplane revealed that it was not equipped, nor was required to be equipped, with a nose landing gear (NLG) ground contact switch intended to preclude in-flight operation of the thrust reverser (T/R). The left T/R door was found unlatched and open, and the right T/R door was found closed and latched. Further, electrical testing of the T/R left and right stow microswitches within the cockpit throttle quadrant revealed that the left stow microswitch did not operate within design specifications. Disassembly of the left and right stow microswitches revealed evidence of arc wear due to aging. Based on this information, it is likely that the airplane’s lack of an NLG ground contact switch and the age-related failure of the stow microswitches resulted in an asymmetric T/R deployment while on approach and a subsequent loss of airplane control. Also, there were additional T/R system components that were found to unairworthy that would have affected the control of the T/R system. Operational testing of the T/R system could not be performed due to the damage the airplane incurred during the accident. Toxicology testing results of the pilot’s specimens indicated that the pilot had taken diazepam, which is considered impairing at certain levels. However, the detected amounts of both diazepam and its metabolite nordiazepam were at subtherapeutic levels, and given the long half-life of these compounds, it appears that the medication was taken several days before the accident; therefore, it is unlikely that the pilot was impaired at the time of the accident and thus that his use of diazepam was a not factor in the accident.

Quoted verbatim from the NTSB record.