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Information for operators of R22 and R44 helicopters
- There are engine performance issues affecting some helicopters operating in northern Australia
- Based on the information currently available R22 and R44 helicopters remain safe to operate, providing they are flown within their operating limitations and maintained appropriately including taking into account the recent CASA Airworthiness Bulletins on these issues
- Operators are encouraged to make yourself aware of these issues and talk to your maintainer to ensure they are undertaking the necessary maintenance including additional recommendations by CASA
What’s the issue?
Premature engine intake and exhaust valve wear has been found in a number of R22 and R44 helicopters used predominately in mustering in northern Australia. In some cases, problems have emerged in less than 100 hours after inspection.
What is the cause of the issue?
Multi-agency work is underway to analyse and address engine performance issues affecting some helicopters operating in northern Australia.
CASA has been working collaboratively with a diverse industry working group to identify the likely cause of the issue.
The group is looking at a range of contributing factors including the way the helicopters are operated, impact on fuel supply changes, and carburettor changes.
This is a complex issue that requires usable data to assess possible causes and to date no definitive cause has been identified. Until these issues are resolved mitigating maintenance actions are recommended.
What action has CASA taken?
CASA has issued two airworthiness bulletins on R22 and R44 engine intake and exhaust valve failures. Intake failures are caused by an intake valve deposit build-up which is likely occurring during extended ground operations in elevated ambient temperatures. A failure to observe adverse indications or unusual engine behaviour may result in an induction backfire, engine power loss and airframe yaw. In a severe event this could lead to several uncontrolled power and yaw reactions. CASA has made a number of recommendations to address this issue.
Exhaust valve wear may result in the situation developing to a point where cracks or large chips can form around the edge of the valve face or cause the valve head to separate from the stem with sudden and complete loss of cylinder compression and partial or complete engine failure. CASA has also made a number of recommendations to address this issue.
Based on the information currently available R22 and R44 helicopters remain safe to operate, providing they are flown within their operating limitations, and maintained appropriately including taking into account the recent CASA Airworthiness Bulletins on these issues. The content and scope of these bulletins is based on preliminary investigation findings and may be updated as additional information becomes available.
With the assistance of the engine manufacturer Lycoming and helicopter operators five engine monitoring devices are being fitted to mustering helicopters operated in northern Australia. The data collected by the devices will provide detailed information on engine performance trends to allow a more comprehensive analysis of the issue. Further work continues on other potential contributing factors including fuel and operating conditions.
What should I do?
It’s important that you make yourself aware of the issues, the mitigators in place described in the airworthiness bulletins, and work that is underway. We recommend you speak with your maintainer about these issues.
We will provide further information to operators through existing channels such as Airworthiness Bulletins and Airworthiness Directives.
- Airworthiness Bulletin – engine intake valve (AWB 85-025 Issue 2, 13 December 2018)
- Airworthiness Bulletin – piston engine exhaust valve and valve distress guide (AWB 85-024, 2 August 2018)
- CASA briefing newsletter – December 2018
- Lycoming cylinder durability investigation group defect report form 1529 (pdf 265.75 KB)