• Pilot Nigel Frederickson, 74, died after his plane’s propeller detached mid-air during a test flight.
• The coroner found fatigue cracking in screws securing the propeller flange to the crankshaft.
• Coroner Rachael Schmidt-McCleave urged operators to re-familiarise themselves with Civil Aviation Authority publications about design changes to aircraft.

The pilot of a home-built plane died in a crash two hours after fitting a new propeller, which fell off the aircraft in mid-air.

A coroner has found that Nigel Frederickson, 74, died from multiple injuries sustained in a crash on August 17, 2020, while desperately trying to land his propeller-less plane at the Ōtaki Air Strip about 70km north of Wellington.

His badly damaged aircraft was found by rescuers upright on the field in long grass halfway down and at right angles to the airstrip, with a trail of debris leading back to where it first impacted the ground about 50 metres away.

The front of the plane and the right wing tip sustained extensive damage. The fibreglass windscreen was smashed, exposing the cockpit.

The propeller was missing and a search failed to find it.

Frederickson was still in the pilot’s seat. He was declared dead at the scene by a rescue helicopter medic.

The retired engineer had built the all-metal construction two-seated Sonex aircraft from a kit between 2007 and 2009.

A Civil Aviation Authority (CAA) air accident report said he held a private pilot’s licence with 20 years and about 600 flying hours of experience, more than half of them in the Sonex aircraft.

Nigel Frederickson had built the Sonex aircraft from a kit between 2007 and 2009.

Frederickson, a married man with two adult children, stored his aircraft at the Ōtaki Air Strip hangar, which he part-owned.

He left home around 9am on the day of the crash, telling his wife he was going flying. His son had talked to him the night before and discussed them going flying together, but in the end, only the father went.

Propeller not approved

Frederickson intended to fit a new propeller to the aircraft, wanting to increase its rate of climb, and then do a test flight afterwards.

The Sensenich fixed-pitch, two-bladed wooden propeller was not approved to be fitted to the Jabiru 2200A engine which powered the aircraft.

A forensic examination later found most of the screws securing the propeller flange to the engine crankshaft showed evidence of fatigue cracking.

There were no positive location dowel pins, leading to additional loads being transferred onto the screws.

Some of the screws failed, resulting in the propeller detaching from the aircraft.

Closed-circuit television footage taken from the airstrip showed Frederickson fitting the new propellor to his plane at 11.07am. The crash happened two hours later, at about 1.05pm.

The CAA report said a test flight began at 12.48pm.

Nigel Frederickson's aircraft crashed at the Ōtaki Air Strip, to the east of State Highway 1 about 70km north of Wellington. Photo / Google Maps

Frederickson flew to a point about six nautical miles (11km) northeast of the airstrip at a height of 3000 feet. He then turned and made a shallow descent back towards the landing strip.

About 17 minutes after take-off “the propeller detached from the aircraft”, the coroner’s report said.

Neither the coroner nor the CAA accident report identified how long this happened before the crash but they indicated that Frederickson was able to continue flying the disabled aircraft as it approached the strip.

Frederickson would have been suffering anxiety and “startle effect” – an aviation term which describes how an emergency might disrupt appropriate decision-making – as the situation unfolded, the CAA report said.

‘Unthinkable and frightening event’

“The pilot had no prior knowledge of how his aircraft would perform without a propeller,” it said.

“The loss of a propeller would, in any circumstance, be an unthinkable and frightening event, and the situation cannot be trained for.

“More importantly, the pilot could only do the best he could to salvage a situation he had not experienced before.”

Frederickson made a series of S-turns to lose height but with only a short distance to the runway and aggravated by a tailwind, he was still too high as he approached.

Faced with some urgency, the CAA report said he likely placed the aircraft into a sideslip in an attempt to land within the confines of the runway.

It said he probably lost control during this final maneouvre while attempting to make an emergency landing.

Frederickson had CAA authority to maintain his aircraft, which had an airworthiness certificate following an inspection in 2019.

However, he was not approved to make design changes to his plane, which would have included fitting a propeller which changed its operational characteristics.

Fitting such a propeller would have also invalidated the airworthiness certificate.

Coroner Rachael Schmidt-McCleave urged aircraft operators to re-familiarise themselves with CAA documents about what constitutes a design change, and the conditions of airworthiness certificates and operator requirements.

“If there is any doubt as to whether a change [to an aircraft] constitutes a modification, I encourage operators to consult with the CAA before making the change and attempting a flight,” she said.

Ric Stevens spent many years working for the former New Zealand Press Association news agency, including as a political reporter at Parliament, before holding senior positions at various daily newspapers. He joined NZME’s Open Justice team in 2022 and is based in Hawke’s Bay.