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Exhaust spring replacement

Posted: Mon Oct 02, 2017 3:13 pm
by TakeTwo
Hi, everyone. I recently became the owner of a Tecnam P2004 Bravo, and I have a couple of questions. During an orientation flight, the instructor pointed out that an exhaust spring was missing;it was quickly replaced by their shop. Now, 15 or so hours later, I have noticed that another spring is missing. Is this going to be a common occurrence? Is this a "get-it-fixed-now" situation? (I ask because I have read of situations where 2 or more were replaced at a scheduled inspection.) Assuming the proper length is available, are the springs found at Lowe's etal acceptable? Can I, as the a/c owner, legally replace them. What else should I know? Thanks.

Re: Exhaust spring replacement

Posted: Mon Oct 02, 2017 5:41 pm
by drdehave
They are prone to self-consume, due to vibration. Properly coating them with red, high-temp silicone helps to dampen them and prevent self-destruction. Google it and learn how to apply the silicone. Replace them right away; failure to do so can lead to other vibration-related issues. Get springs from a Rotax supplier, such as LEAF or CPS, not your local hardware store. Can YOU put them on/off? That should be in your aircraft maintenance manual, as it is an LSA manufacturer's decision. I would also encourage getting a spring installation tool and extra springs to carry with you. Just my 2 cents.--Rich

Re: Exhaust spring replacement

Posted: Wed Oct 04, 2017 8:47 am
by TakeTwo
Thanks for the information.

Re: Exhaust spring replacement

Posted: Thu Oct 05, 2017 8:39 am
by roger lee
Your springs are coming off because they need to be stretched a tad more. You shou should have about a fingernails space between each coil. If not take a hammer or pry bar and bend the loops on the exhaust a little wider open. Then safety wire should be run down through the center of the spring. This keeps all springs or parts if they break or fall off off the runway and taxiways. Then apply high temp silicone. DO NOT fill the spring with silicone. This allows the spring to get too hot and not be able to dissipate heat and usually causes premature breaks. Apply the silicone about 3/8" - 1/2" wide and about 1/8" - 1/4" tall. Work it into the spring coils. This will help dampen vibration and keep it in one place.


https://photos.google.com/photo/AF1QipM ... b25YP2BXvd

Re: Exhaust spring replacement

Posted: Thu Oct 05, 2017 9:25 am
by drdehave
And Harbor Freight Tools carries that Red Hi-Temp Silicone--and it's dirt cheap (which, I guess, could reflect on its quality--but it's been working just fine for me :lol: ).

Re: Exhaust spring replacement

Posted: Thu Oct 05, 2017 9:45 am
by roger lee
You can buy the high temp silicone in black or red and at any auto parts store or Ace hardware.