FlyHelio

General Category => General Helio Discussion => Topic started by: yukonranger on October 28, 2018, 07:49:56 PM

Title: Exhaust Studs and Nuts
Post by: yukonranger on October 28, 2018, 07:49:56 PM
Hello, my, late serial number, H295 has 5/16x24 brass nuts on the exhaust studs.  I have seen Helios with steel nuts on the exhaust studs. What is the correct nut and stud? 

Thanks

Title: Re: Exhaust Studs and Nuts
Post by: jmetzler on November 01, 2018, 09:39:05 AM
The nut called out by Lycoming is an STD37. The Helio parts manuals (military and civilian) call out AN121503. Both STC37 and AN212503 are plain steel nuts. Both will corrode and sometimes bring the stud out with them when removed. I've seen brass used, our preference is the MS21046C5 per minor alteration, which is a stainless steel self locking nut. They don't rust, don't need lock washers and come off nicely. Studs come in all kinds of oversize on the thread going into the cylinder.
Title: Re: Exhaust Studs and Nuts
Post by: yukonranger on November 07, 2018, 08:10:31 AM
Thanks Jim.  I see CRES studs are availible too.  Do you recommend those?

Mike
Title: Re: Exhaust Studs and Nuts
Post by: jmetzler on November 07, 2018, 03:10:20 PM
I'd definitely use corrosion resistant nuts. Jim