[Poland308]

I don’t disagree 70 or 80 S2 will work just fine I don’t disagree 70 or 80 S2 will work just fine. based off of my personal experience in the pipe industry my procedures always called for matching filler in that application. I understand it’s no different than using something like 309 on a carbon steel.

[VA-Sawyer]

Just for kicks, I looked in an old copy of AC 43.13 Acceptable Methods of Aircrafr Alterations and Repair. The chapter on welding calls for ER 4130 when doing tubing repairs. That suprised me.

[Oscar]

Just for kicks, I looked in an old copy of AC 43.13 Acceptable Methods of Aircrafr Alterations and Repair. The chapter on welding calls for ER 4130 when doing tubing repairs. That suprised me.

Using which welding process? And does it specify a necessary PWHT?

[VA-Sawyer]

Welding process wasn't specified. I didn't see a post weld HT.
I used to deal pretty often with Harrison in Indiana. They repaired a lot of aircraft cylinders by welding. They had a number of 'In House' FAA approved procedures. They also had a number of 'Gentlemen Agreements ' with the FAA about what could be repaired, and what couldn't. I learned a lot, every time I visited the place.

[dmeray1@hotmail.com]

Thanks everyone. In the process of fixing the crack by the bearing hanger I found a crack just aft of the motor mount. I did stop drill holes and ground a V following the cracks. The two cracks were within an 8 inch section of frame. With a 40 horsepower engine with chain drive and a six speed transmission I decided to insert a "stuffer" tube to beef up the area. I used a 1 inch diameter .120 wall DOM tube and secured it with a couple of rosette welds. Hopefully it won't crack somewhere else.