P-70 starter weird sound
 

Hello,

I have a P-70 installed on my Boomerang Intro which have been running faultlessly. The jet had not been flown for a couple of years. 2 weeks ago i had 2 flights on it which were perfect and turbine started (kero start) from 1st attempt.
Last week after a successful flight, and during cooling down process, i heard a weird sound which apparently was coming from starter unit.
I haven't attempted another start, and would like to know what to do hoping that i will not have to send motor for service as this would be cumbersome and expensive for time being (still a lot of hours to reach the first 25 hours service).
BTW, compressor blades are turning smooth and free.

Appreciate your feedback/suggestions on how to deal with this issue.

Regards,

Check the condition of the starter rubber O ring.
With the engine not being used for two years, the rubber ring may have dried out & perished, especially as you live in a hot climate.
Also check that the starter bendix is not sticking.

Jim,

thanks, how exactly do you recommend to do the checking?
Sorry for having limited knowledge in servicing turbines.

Thanks in advance

The easiest way is to ask another more experienced jet modeller in your area to have a look at the starter. Perhaps someone at your club?
The O ring is located in a groove at the turbine end of the starter. When the starter spins, that end of the starter is thrown out by centrifugal force, to contact the nut on the front of the turbine. The starter rubber ring is the contact point on the turbine & spins up the turbine to initiate the start sequence (also connects to cool down the turbine when you shut down the turbine) .
This video shows a typical starter. The video is about a Wren turbine, but the Jetcat starter works the same way. Look at the first couple of minutes & you will see the relevant working parts.
If the rubber O ring looks cracked, or damaged, replace it. You may be able to get one the same size from a hydraulic shop.
Check that the Bendix (called clutch in the video) is moving backwards & forwards freely.
Usually the noise of a starter requiring attention, is a screeching sound.
Do a search on this & other forums for servicing turbine starters & replacing O rings.

Here is the link mentioned earlier.
https://www.google.co.uk/url?sa=t&rc...r3a_6czKVhwzUg

Jim,

thank you for taking the time to reply extensively and clearly. Unfortunately, i am the only one flying turbine jets in Lebanon (for time being at least) and learning process have been exclusively through research and reading. it has not been easy at all for sure but i am happy to say that i have come a long way and got acceptable results so far!!!

Will dig more and do research on other forums on the subject

Best regards,
Dany