Dstl working to protect helicopter engines from sand erosion

The UK’s Defence Science and Technology Laboratory (Dstl) is contributing to a project set up by The Technical Cooperation Panel (TTCP) to investigate erosion-resistant coatings as a potential solution to protect helicopter engines from sand erosion.

Desert conditions pose a significant challenge to helicopter engines, particularly during take-off and landing when gas turbine engines in helicopters suck in air from the surrounding environment that contains sand particles damaging to the engine’s components. The engine is forced to work harder to compensate for engine components damaged by sand erosion, burning more fuel and struggling to produce the required power. 

These sand-eroded components need to be replaced more often, resulting in costly repair bills and loss of capability as helicopters are taken out of service for maintenance.

Dstl’s contribution to the TTCP project being undertaken to solve this issue has been to design and conduct effective and reliable rotating bend fatigue tests that would indicate the relative strengths and limitations of a number of commercially available coatings. Dstl identified that the University of Birmingham had suitable facilities within its Metallurgy and Materials Department to support this work.

According to Dstl, rotating bend fatigue tests are a quick and inexpensive way of building up a large number of fatigue cycles in small specimens. A bending stress is applied to a small rotating specimen and as a consequence each rotation is a fatigue cycle. Since the specimen is rotating at 3,000 revolutions per minute, a test of one million cycles can be conducted in around eleven hours. 

A number of tests have been undertaken in Australia, Canada and New Zealand, looking at  commercially available products. Industry suppliers have applied their coatings to the test substrates; in exchange, they will find out how their coatings performed in five tests undertaken so far and have ongoing support from the international defence organisations, helping them to improve their technology for defence applications.

Dstl is also considering how erosion-resistant coatings might be deployed in conjunction with inlet protection, and investigating the costs and benefits of different approaches.