[Peetwo]

No.29 from list completed; plus the Oz reports on AO-2022-054!! - 

From this week's DTS Stewie Macleod...

Tail rotor driveshaft failure demonstrates how unusual sounds and responses can be an indication of an imminent system failure



Brief, loud grinding noises precipitated the failure of a Bell 505 helicopter’s tail rotor driveshaft, an Australian Transport Safety Bureau report details.

On 15 July 2022, the Bell 505 was being used for a scenic flight from Cairns, Queensland, with a pilot and two passengers on board.

About 30 minutes into the flight, near Double Island, the pilot heard two brief, loud grinding noises, and elected to return to Cairns Airport.

Over the airfield, the grinding noise returned, and after 10-12 seconds, while approximately 10 ft off the ground, the pilot heard 2 loud bangs.

“In response, the pilot moved the throttle to idle, which stopped the yaw,” ATSB Director Transport Safety Stuart Macleod explained.

A run-on landing was performed on the grass short of the assigned helipad, and a subsequent inspection of the helicopter revealed the tail rotor driveshaft had failed.

“The ATSB determined that during landing, a combination of heat and torque due to a seized forward fan shaft bearing resulted in failure of the fan shaft just aft of that bearing,” Mr Macleod said.

Due to the amount of damage on the failed bearing, the ATSB was not able to identify the reason for the seizure, and the manufacturer, Bell Textron, advised the ATSB that it was not aware of any previous instances of bearing failure in 505 fan shaft bearings.

“Unusual sounds and responses from an aircraft can be an indication of an imminent system failure,” Mr Macleod continued.

“In this instance, the pilot’s decision to return to Cairns was probably influenced by the initial short duration of the unusual noises and overwater operation. While a safe landing on an airfield resulted, the occurrence also illustrates how quickly failures can occur.”

Mr Macleod noted pilot’s decision to adopt a shallow approach, and to reduce throttle immediately following the shaft failure, both assisted in controlling the helicopter following the uncommanded yaw, and allowed for a safe landing.

“This incident does highlight that pilots experiencing any unusual vibration or noise should land as soon as possible and have the aircraft inspected prior to further flight,” he said.

“If an immediate landing is not possible then pilot should be prepared to conduct an emergency landing or ditching if the situation deteriorates.”

Read the report: Tail rotor driveshaft failure involving Bell Textron 505, VH-VTB, Cairns Airport, Queensland on 15 July 2022[/size]

Publication Date
19/05/2023

This investigation was completed in another record completion time for the ATSB IE 10 months and 14 days. However it was still non-compliant with ICAO Annex 13 as there was no prelim report.

Comment from a SME:

"..Mmmm, out in good time only because they can’t determine what caused the shaft failure. I'm sure Bell weren’t to interested in sharing their dirt! Instead we get the gold advise to land if you hear banging noises. Duh!.."

As a point of comparison, for what is a NTSB version of a 'Short (desktop) Investigation', the following prelim report, with virtually zero media fanfare, was released yesterday:

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Note that short factual prelim report took 2 weeks to produce. Will monitor the progress of this investigation...

Next, I note that the Oz has reported on the PelAir Flinders Island RTO Final Report...

Pel-Air pilots reschooled on aircraft parking brake after aborted takeoff

A six-month investigation by the Australian Transport Safety Bureau has found a charter flight to Tasmania was unable to takeoff because the pilots had not released the parking brake.

The Pel-Air operated Saab 340 had two pilots, a cabin attendant and 25 passengers on board, when the takeoff from Flinders Island was rejected because the plane was veering to the left and not accelerating sufficiently.

The Flinders Island airport operations officer reported seeing smoke coming from the aircraft’s wheels and radioed the flight crew to tell them.

“The first officer also recalled the aircraft felt like it was braking by itself, and that pressure was felt in the brake pedals under their feet,” said the ATSB’s final report.

The Saab 340 reached a speed of 96kts, or 177km an hour, before the takeoff was rejected more than a kilometre along the runway.



When the aircraft returned to the gate, the pilots noticed all four main landing gear tyres were deflated and significant tyre marks on the runway from the 300m mark to 1150m.

ATSB director of transport safety Stuart Mcleod said their investigation found the parking brake handle had not been fully released, resulting in residual pressure remaining in the brake system.

“As the aircraft accelerated for takeoff, this heat generation increased significantly, resulting in further application of the brakes,” said Mr Mcleod.

Since the incident on November 4, 2022, Pel-Air had taken a number of safety actions to prevent a reoccurrence, the ATSB noted.

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While on the subject of PelAir and the ATSB, I note that the 10th anniversary of the tabling of the infamous Senate PelAir report will occur on the same day that RRAT Budget Estimates should be reviewing the recent inept, shambolic performance of Popinjay and the ATSB -  : Budget Estimates: Popinjay & AMSA dodge Senate Estimates - WTD??   

Reflect on this speech by Senator Fawcett not long after the tabling of the Senate AAI report:

 

A decade down and what's changed? - I would argue that the state of aviation safety administration and investigation is WAY WORSE!! 

MTF...P2