MT prop overhaul or “IRAN”?

[Kooshball]

It is time for an internal inspection and dressing up / repairing of the blades on my MTV-12-B / 183-59 prop. Full overhaul is quite expensive and seems to include many items needed for certified commercial operators. From a safety standpoint, am I giving up anything by going the IRAN route to include stripping, repairing (if needed) and repainting the blades?

Not trying to cut corners but This prop only has 700-hours on it but is way past the 6-year TBO on calendar time. I don’t want to pay for replacement parts That really are not needed yet at it will take me 15-more years to get to the 2000 hour point but I’m not willing to sacrifice safety either.

Thx in advance!

[FORANE]

I have a MT overhauled by mt usa deland and experienced paint peeling off in sheets shortly after. Ended up taking it to an auto body shop for strip and repaint. I would opt for an IRAN, and would avoid MT Deland.

[9GT]

My buddy with the Cozy MKIV had his MT prop overhauled by Tiffin Aire in Tiffin Ohio. Their work was outstanding and they actually stripped the blades all the way down to the cores and re-glassed them before paint. That was about 5 years ago and everything is holding up very well. They were very reasonable in the overhaul money wise.

[FORANE]

2nd vote for Tiffin. Thats who I go to today for MT service, parts.

[gmcjetpilot]

Save your money. The prop is safe at 700 hours. I assume it has no damage and you hanger your plane (and prop)?

Read this from Savvy Aviation, Mike Busch. He is well respected.

https://resources.savvyaviation.com/..._intervals.pdf

I have run engines and props over recommended TBO without issue, however it is done carefully.

Props, like MT with wood and composite blades are not as fatigue critical as all metal props. However age does affect them, but yours being hangered (I assume) the actual "age" is less than chronological age. Inspect in situ for obvious damage. The hub? 700 hours on hangered plane it is not an issue, unless there was an existing manufacture defect. Time is critical for props sitting out in rain, snow, direct sunlight, high temps and humidity, for year after year, decade after decade.

This advise is at your own risk of course.... however unless you are commercial Ops you do not need to follow the TBO unless there is a AD on the prop.

Over TBO Engines I got oil analysis and did more frequent compression checks. I always monitor oil use. You know not to add more than 6 qts in a Lyc 4 banger right. With Eng Monitoring systems you can look for trends.

Props on my old twin were also over TBO. The props in question had an AD for a onetime tear down inspection. They found out of 4 blades (two two bladed props) they found small corrosion pits on one of the 4 blade shanks. Fortuitously the prop shop had a serviceable used spare blade. They complied with SB and inspected it. I think I also had to replace the bearings and seals. In other words R&R as required not a full overhaul. Would a corrosion pit on blade shank cause a crack? May be over a long period of time. BTW these props were over 30 years old with about 4000 hours. This plane was not babied.

[Kooshball]

Originally Posted by gmcjetpilot

Save your money. The prop is safe at 700 hours. I assume it has no damage and you hanger your plane (and prop)?
.

Thx for the note! The plane has been hangared its whole life but not in a climate controlled hangar so it will still get temp and humidity swings just no UV or direct precipitation.

I don’t see any structural damage but there is paint erosion on the tips and cracking of the black paint on the rear of the blades starting at the tip and following the rear of the metal insert where it terminates. Being wood composite I wanted to properly address the paint cracking and erosion before they go deeper. I was surprised when MT USA said they can’t repair anything out of TBO, only option from them is full certified overhaul which seems excessive.

I’ll definitely check out that article though!

[9GT]

Originally Posted by Kooshball

Thx for the note! The plane has been hangared its whole life but not in a climate controlled hangar so it will still get temp and humidity swings just no UV or direct precipitation.

I don’t see any structural damage but there is paint erosion on the tips and cracking of the black paint on the rear of the blades starting at the tip and following the rear of the metal insert where it terminates. Being wood composite I wanted to properly address the paint cracking and erosion before they go deeper. I was surprised when MT USA said they can’t repair anything out of TBO, only option from them is full certified overhaul which seems excessive.

I’ll definitely check out that article though!

Check with Tiffin Aire to be sure your prop has the newer style hub bearings. My buddies had the old style and they were replaced at around 3 years (200 hours) of use when the blades started to wobble. His prop is about 13 years old now.

[mike newall]

Irrespective of the hours - calendar life is calendar life. It needs an inspection - no extensions. Too many whirling bits and tiny ball bearings that can go rusty

In UK/Europe we have a low hours inspection protocol which is supported by MT for props just like this.

We did ours and it was around $1500 including a load of balls that needed replacing. It is basically a stripdown, inspect, regrease and assemble unless they find anything.

Do not ignore the calendar inspection - an engine faltering is one thing, a prop losing a bit is probably terminal - your choice