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State of Aviation Safety Downunda - 

Via Oz Flying:

CASA issues On-Condition Reminder
24 July 2024


CASA this week released an Airworthiness Bulletin reminding engineers about the monitoring requirements for on-condition maintenance.

AWB 02-001 dated 23 July was issued in response to an ATSB investigation into a fire and fatal crash involving a Mooney M20 near Luskintyre, NSW, in 2022.

The AWB states that some engineers appear to have forgotten that "on condition" requires active monitoring such as repetitive inspections or tests to ensure the component or system remains functional.

"Some operators and maintainers, including some Licensed Aircraft Maintenance Engineers (LAMEs) have come to believe that 'on condition' means fit and forget," the AWB points out. "They believe that it’s OK to not do anything until a failure occurs.

"Maintenance practices that mistakenly equate 'on condition' to mean 'fit-and-forget' and/or 'fit-until-failure' will not achieve the levels of safety and reliability that are inherent in the design of the aircraft.

"At best, this may cause operational surprises, which could prove very costly. At worst, this may jeopardise the safety of an aircraft and its occupants."

On-condition maintenance refers to the inspections and checks used to detect degradation in condition or performance. Items are left in service on the condition that they continue to meet a desired physical condition and performance standard.

Most commonly, engines of aircraft in the private and air work categories can be run on condition, which enables the aircraft owner to bypass the TBO time provided an engineer is satisfied with the engine. An engine needs to be re-inspected and signed-off again at the next periodical check.

"The item's performance may relate to, but are not limited to, cleanliness, cracks, deformation, corrosion, wear, pressure or temperature limits, leaks, loose or missing fasteners, and are published in the approved data of the aircraft or aircraft component," the AWB states.

"Therefore on condition maintenance means an inspection / check that may result in the removal of an item before it fails in service."

Mooney VH-UDQ crashed in 2022 after an O-ring on the engine-driven fuel pump failed due to deterioration, causing a fire in the engine compartment. Although the pilot attempted an emergency landing, the aircraft struck trees short of the airport. The pilot later died in hospital.

Here is a link for the AWB published on the 23 July: https://www.casa.gov.au/sites/default/fi...enance.pdf

Couple of OBS on this AWB associated with an ATSB SAN issued in conjunction with the final report of 'Short investigation' AO-2022-049.

To begin this was the bollocks fictional Popinjay media release associated with release of the final report:

ATSB urges proactive approach to replacing elastomer components after O-ring failure contributed to Luskintyre in-flight fire accident

Piston aircraft operators and maintainers are urged to proactively replace O-ring seals within fluid-carrying components of their aircraft before they naturally deteriorate from age, after a Mooney fatal in-flight fire near Luskintyre, NSW on 17 October 2022.

The ATSB has issued the safety advisory with the release of its investigation report from the accident where a pilot was fatally injured when the Mooney M20J they were flying caught fire in flight, and collided with terrain short of the runway at Luskintyre Airfield.

The Mooney had taken off from Maitland for a local flight, and flew to and around Cessnock, before heading north-east to Luskintyre.

“The Mooney had just completed a left orbit of the airfield when witnesses observed the aircraft descending to land, and reported seeing smoke and flames trailing the aircraft,” ATSB Chief Commissioner Angus Mitchell said.

The aircraft collided with terrain near the threshold of Luskintyre’s runway 30. While the pilot survived the collision, they later succumbed to injuries associated with an intense post-impact fire.

“The ATSB investigation determined fuel leaking from an age-affected O-ring seal of the engine-driven fuel pump ignited and caused an engine compartment fire,” Mr Mitchell said.

“A leak from the pump outlet fitting that supplied the engine fuel control unit was identified, and analysis indicated the O-ring sealing that fitting had deteriorated with age.”

Piston engines, and the components necessary for their operation, installed in aircraft operating in the private or airwork category are permitted to remain in service beyond their recommended calendar time overhaul interval, the investigation report notes.

Aircraft records indicated the pump had been in service for more than 29 years and had likely remained undisturbed for maintenance throughout that period.

“Inspect the uninspected,” Mr Mitchell said.

“If aircraft records identify elastomer – rubber-based – type components that have remained undisturbed for significant periods of time, take a proactive approach – replace components such as O-ring seals before they deteriorate to the point of failure.”

The ATSB’s final report also notes the finding that the aircraft had been recently refurbished.

“This refurbishment included repainting the aircraft, and replacing interior furnishings with alternate materials, but neither the refurbishment, nor the flammability assessment of the substituted materials, were recorded in the aircraft’s log books,” Mr Mitchell explained.

“While the effect this had on the in-flight fire or survivability in this case could not be determined, aircraft owners should be sure to document refurbishment action in the log book, and include details of materials if substituted, as well as their suitability for use in aircraft interiors.”

Read the report:  In-flight fire and collision with terrain involving Mooney Aircraft Corporation M20J, VH-UDQ, near Luskintyre Airfield, NSW on 17 October 2022

Read the Safety Advisory Notice: On condition? Replacing O-ring seals before age catches up.

Publication Date
07/05/2024

Notes: 

• The 'Short' investigation had no associated preliminary or interim reports and took 18 months and 21 days to complete. One wonders when the investigators discovered the leaking age effected fuel O-ring seal?? 
  
• The issue date for this important SAN was on the same day the final report was released IE 07/05/24
  

Safety Action by the Civil Aviation Safety Authority

In response to the investigation finding related to deteriorated O-ring seals, the Civil Aviation Safety Authority proposed to review Airworthiness Bulletins AWB 02-001 and AWB 85-004 and most likely update them. The update would serve as a reminder to industry of some of the concepts and philosophy related to ‘on-condition’, which is not a ‘fit and forget’ approach to preventative maintenance.  

• It took CASA at least 78 days to 'review' and 'update' the AWB on a safety issue that was most likely identified within weeks of the accident occurring.
  

Our state aviation safety system in action - we're definitely the envy of the world...

MTF...P2