MT propeller AD 2022-18-02

[Rich]

This was recently issued and references a long-existing MT Service Bulletin from 2014 (latest revision 7). It affects a relatively small number of props/blades manufactured or overhauled in 2014 (listed by serial numbers) that are thought to have one or more defective lag bolts (identified by part number) which could fatigue-fail due to improper anti-corrosion treatment. Mine isn't included, but since it's been 7-1/2 years since its last overhaul we'll be pulling it for overhaul and making sure the offending part number bolts aren't in this prop. Failure of these bolts has been known to cause blade departure. I don't know of any accidents that have been caused by this problem, but still.

[jwx96]

Thanks Rich. I checked my logbook and my MTV-12-B prop was overhauled during the specified time period by the MT service center in Florida. I looked at MT SB 30, revision 7 and fortunately my prop serial number is not included in the list of props with the bad lag bolts. I did have a loose blade this year after an overhaul at a local MT service center and sent the prop to Florida for a repair. The specifics of what they found and repaired are in the WO at MT and not in my logbook, but there is no mention of any of the lag bolts being replaced. It sounds like these bolts are pretty important. I hope your overhaul goes well.

[Rich]

Propless and governorless. 100% change in climb rate and cruise speed. The prop will be done by American Propeller on Redding, CA. And they pick up and deliver here. Given the shipping cost for these things this is not a small matter.

[Steve]

I have been lucky. Two overhauls, both done by my local shop - Jordan Propeller. They are an MT dealer and service center, and come to my hanger to pick up and deliver the prop. I also had the opportunity to tour their shop before I had them do the first OH, and was very impressed with the cleanliness and organization of their shop. Plus, they were doing two MT props at the time (a DA42, I think) so I could observe some of the process.

While the prop is off, you might consider replacing the alternator drive belt...

[Rich]

While the prop is off, you might consider replacing the alternator drive belt...

Correctomundo. Already ordered. Expected arrival this afternoon.

[jwx96]

Yes, I replaced the alternator drive belt when my prop was off too. It seemed like the thing to do.

[Rich]

I just heard the hub on my prop has excess corrosion and it will need a new hub, so the quote is $10K. Better than getting a new prop, anyway. For grins I'm trying to price the newer model MT: MTV-12-B/183-59B. Anyone have any insight?

[Steve]

Rich:

When I had the blades on my prop switched out for the 183/59b blades, the cost per blade was $3K. I received a minimal credit for my old blades, which were damaged, but repairable (the cost to repair was within $1K of the total cost for new blades, therefore my decision to upgrade was easy). The shop also discovered that the blade hub bearings were worn, and needed replacement, at a cost of $406 x 3 in addition to the overhaul costs. This was 2 years ago.