Schweizer 269C N9WZ

Summary

On 1 July 2023 at about 16:00 local time, a Schweizer 269C registered N9WZ was involved in an accident near Macclenny, Florida, United States. 3 people were 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

1 July 2023 at 16:00

Classification

Accident

Location

Macclenny, Florida, United States

Coordinates

30.2758, -82.1267

Aircraft

Schweizer 269C

Registration

N9WZ

Category

Helicopter

Year built

2005

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

ERA23LA284

1 person had minor injuries.

The improper maintenance of the landing gear dampers and main rotor elastomeric dampers, resulting in ground resonance during an unsuccessful takeoff attempt with the helicopter near its maximum gross weight for the density altitude.

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

Read the full NTSB narrative

According to the pilot, he flew the helicopter to the accident site earlier in the day with no anomalies noted during the preflight inspection, the flight itself, and the post-flight inspection. He said he briefed and loaded two passengers, which placed the helicopter near its maximum allowable gross weight and near its forward center-of-gravity (CG) limit. The pilot attempted the engine start but “inadvertently stalled the engine” during main rotor engagement. After the rotor stopped, he performed an engine start, rotor engagement, run-up, and a “ground check with no defects noted.” The pilot said when he started to raise the collective control for takeoff, he felt a “very slight vibration that subsided instantly” but he lowered the collective, performed a magneto check, checked the gauges, felt for any vibration, and listened for any malfunction. Everything seemed normal so he initiated the takeoff again. The pilot reported that as he began to raise the collective an “extremely violent” left-to-right rocking motion began. The pilot considered lifting the helicopter into the air in case the helicopter was in ground resonance, but he believed that the helicopter had experienced “a major malfunction and not ground resonance.” He lowered the collective, reduced the throttle to idle, and the helicopter, which had not left the ground, “disintegrated.” A witness recorded a 21-second video that showed the seconds before the accident and the accident itself. Sounds consistent with engine and main rotor operating rpm were heard before both rpm signatures appeared to droop as the helicopter became light on the skids and rotated nose-left around the main rotor mast about 20° before it settled to the ground. The helicopter then instantaneously rocked left and right, the main transmission and mast assembly became free of its mounts, and the turning main rotor destroyed the tailboom. A detailed examination of the wreckage and the maintenance records revealed damage consistent with a ground resonance event, and damage/degradation of main rotor elastomeric dampers and the landing gear dampers that predated the event. It is likely that the degraded condition of the dampers accelerated the helicopter's entry into ground resonance during the pilot's takeoff attempt. The records also revealed improper maintenance and missing entries for mandatory inspections. The sequence of events, the observed pattern of the helicopter’s self-destruction, and the damage signatures were all consistent with ground resonance. The loading of the helicopter near its maximum gross weight and the relatively high density altitude additionally compromised the control and power margins available to the pilot during the attempted takeoff.

Quoted verbatim from the NTSB record.