by N3322G » Sun May 22, 2016 1:46 pm
Mmm, haven't had good expreince with AWI in terms of having their work last.
Heads up on AWI repairing TwinCo exhaust stacks. Both outboard, forward cylinder stacks cracked just below the cylinder attachments on each engine.
Here are the details of the history.
A shop adjusted one stack after firewall attachment bolt was found to be extremely worn (think wasp-waisted bolt) due to incorrect bolt material type and inadvertently left it rubbing on the cowl flap. Rubbed a hole before we noticed - guess what's on our pre-flight now for close inspection?
So, as long as we were sending one for repair, we looked at the rest and I decided to send them all. Mistake on my part as it turns out. I had heard that others had difficulty in this process and was promised that the jig made sure the exhaust would fit in the TwinCo cowls.
Nice looking exhaust stacks go back on plane. Ancillary benefit was JPI monitor holes are now more consistently located and they have less conflict with other stuff in the engine area. Took some adjustment to where they didn't whack the Gulf Coast stack extensions.
Within 90 days the #1 on right engine started showing JPI EGT cooler readings. Took awhile to figure it out, everyone thought it was a Champion fine wire spark plug problem - swapped upper and lower but problem persisted. Ran for 8 more months and at annual, the exhaust crack just below the attach and ahead of the EGT probe was barely visible. It was a very sharp-eyed Clifton mechanic that found it. To their credit AWI repaired with a weld even though warranty had expired. I suffered the down time and shipping charges and labor to remove and install. They said the problem was the stack extensions. I commented that the extensions had been on for a decade with zero issues. #1 cyl is forward on the outboard side of the right engine.
Recently, the #2 cyl on the left engine EGT started showing JPI EGT cooler readings. Not huge delta but cooler. #2 cyl is forward on the outboard side of the left engine. Shorter problem diagnosis. Yup. Exhaust cracked in same place as the outboard right engine forward exhaust stack. Since I had been educated, even I could find the problem this time becasue I knew what and where to look.
Pat
Patricia Jayne (Pat) Keefer ICS 08899
PA-39 #10 Texas