Propellers - Overhaul or IRAN?
 

As I understand it, an IRAN is basically a prop overhaul without re-doing the blades?

Everything is pulled apart, inspected, and if ok, seals replaced etc.

The blades are just checked, stripped and painted., but not re-ground or re-bent.


On Ye Olde threaded blades, they CAN treat minor corrosion, so not a death sentence.


On an overhaul they grind material off the blades to make them 'like new.'

BUT, you only get a few OH on the blades, if the material goes below limits.

Is that about right?

So if your blades are in good shape, why not just IRAN periodically?

I'll let someone smarter help answer, Savvy Aviator, here's link:

https://www.youtube.com/watch?v=eNuCcflYTbE

My IA goes with IRAN. It'll discover corrosion just like an overhaul which is the big deal. When I started slinging oil, IRAN was what was done. Plus, I got the idea some parts might have to be replaced with an overhaul..."and good luck finding those, especially for the rear prop" was the quote. Not only cheaper but faster. And local prop guys covered over, short staffed with big backlog. Anything to speed it up helps.

We are a part 135 operator and operate 4 Skymasters now and 6 at one time. We are required to overhaul the props at 2000 hrs. Or 6 years. My props ages average 40 years. So with all the overhauls and dressing during inspections I’ve only had 2 blades be out of limits during overhaul. Not from grinding on it but where the blade seal rubs inside the hub. IRAN is fine but I think after several years of being dress by the average mechanic, they need to be brought back to factory contour.
O I know a lot of maintenance guys that if you mention Savvy to they will tell you to get him to come sign your plane off

Where do you send your props to?

I had a very good experience a year ago with H&S Propeller in White Lake, MI. They overhauled my rear prop of my 1973 C337G. I had a not good experience with Aircraft Propeller north of Chicago the year before and ended up buying a brand new front prop.

Not all shops are willing to do IRAN’s or reseal. I had one shop that required overhaul on any prop that was beyond 10 years since last overhaul. Based on my experience with H&S, I would start there. They seemed quite reasonable and demonstrated a desire to keep old equipment airworthy if at all possible. Good luck! 😊

What concerns (if any) for Ye Olde Threaded Hubs?
 

My front was OH in 2011, and the rear IRAN.

Still very low time in hours.

So obviously in 2011 the parts required for overhaul, were available, ...but may not be now?

Any clues gents?

I recently had my front prop overhauled by H&S as well. Haven't flown it yet but a generally good experience.

The issue with threaded props is that once you pull them apart, you can't put the ferrules back in the same place. So you usually have to find used ones from another prop that was dismantled similarly. And that's getting very difficult to do. H&S had a hell of a time, delaying the overhaul by a few months. If you're interested, I might sell the pair of mine as I've been looking for an excuse to spend otherwise perfectly good money on 3-blade composite props. My marriage is apparently going too well, so...

In Canada for private ops, we are required to overhaul every 10 years of calendar time, regardless of airtime or manufacturer's TBO.

I had my front prop done last winter by BL Aviation outside of Montreal. Great service, final invoice was as quoted.

Rear prop is due next year - will likely go with BL again.

Okay, I will bite.

How much for a pair of spare ready-to-re-use ferrules?

You can email me directly at bigcheese@potomac-airfield.com.