Chunk out of Rear Prop

[Paul Sharp]

Came home through snow, ice, clouds, last night. Looking over the plane after landing and noticed a big chunk of prop missing with torn metal bent funny - when I say big I mean about 3/4" in diameter. This is the rear prop. It did have a previously-filed nick in that spot, but it's definitely a problem now.

Anyone else every have that happen? I'll have to have the mechanics look at it tomorrow and tell me what the options are. Can props be fixed? Or they a "replace" item when they get damaged like that? I assume used ones are on the market?

Promises to be fun....

[FRED-E]

Check with:
Don Nieser
Commodore Aerospace Corp
6221 Commodore lane
Oklahoma City OK 73162
405-722-4079 phone and FAX
405-503-4686 hangar cell phone
nieser.02.337parts@juno.com

for a replacement, the last time I was in The Prop Shop in OKC (about a week ago) Don had some props in there for repair.

Fred N358

[kevin]

From what you describe, you probably will have to replace the blade. You mechanic or prop shop should be able to find you a used blade, and Don is one of the places to look. You have to find a blade that "matches" your other blade, it is not just finding something with the right part number...

Sorry for your trouble, but glad nothing came apart at a bad time...

Kevin

[Kevin McDole]

Paul,

I had a nick in my rear prop earlier this year and since one of my rear cowl fasteners was also missing, I theorized that it departed in flight and went into the rear prop.

My nick was much smaller than your's - perhaps 1/8" x 1/8". Because it was so well defined - with straight edges, it was pretty clear that a rock was not the likely cause.

The prop had to be removed and sent to the prop shop. In my case the damage was small enough that the nick could be filed out. There are rules the prop shops abide by, and the dimensions of the nick dictate whether the prop can be repaired.

Remember, any nut or bolt that falls off is going to go into that rear prop.

Paul:

A couple of years back I was on a cross country and I found a large nick/gouge on the "back side" of one of my rear engine prop blade and a 2" dia. hole on the inside of my right boom about 3 feet back from the prop.

Turns out the thru bolt for the muffler rear support broke and the nut with a section of bolt fell out thru one of the exhaust pipe holes and hit the prop. It took a long time to find the broken bolt.

Bottom line is you need to do a thorough inspection of you engine compartment because more than likely the item causing the damage came out of there.

Regards,

Ray Torres

[Bob Cook]

Paul

Two years ago I replaced the rear engine and a rear prop. On the test flight a bolt flew out of the undercarriage and hit the prop. Total time on new prop : 22 minutes ! Total damage - major.

Murphy says anything in front of the prop will end up in the rear prop. It has an affinity for such matter.

On a new prop you have about 2 inches on the tips and around 3/4 of an inch on the leading edge. There are specific limits. If it is on the face there is more of a problem.

You need to send it to a prop shop for inspection and possible overhaul. They will tell you if new blades are needed. Based on the price of the blades it is almost better to get a new prop rather than old. You have additional cost of putting it altogther again.

Check riley and see if Mary-ann has one that came off an upgrade. They usually have some kicking around.

Word of warning to new pilots. Make sure you do not do a runup on icy surface as the rear prop can ingest ice and it can do considerable damage....

I have reduced FOD by running up the rear engine and at about 30 mph bringing in the front engine assuming the runway is sufficient. I have found far less damage to the rear prop using this approach. I also taxi with mostly the rear engine.

merry xmas to all.

Bob

[Paul Sharp]

Thanks to all for their replies. I did check with Don, and can give Riley a call, too. I didn't think about getting just one blade, and that might save me some money.

I had the mechanics take off the prop and governor and send into the prop shop. So I'll see what they say about the chances for fix (overhaul) or replace. It hasn't been done since 1987, so it was well overdue.

I also asked the mechanics to pull the rear cowlings and do a thorough inspection for anything missing or loose.

That brings up a few questions:

1 - How often do others get their props/governors overhauled? I think the TBO is five years (don't know if there's an hour limit or not), but obviously you can go longer if you're not flying for hire.

2 - The little screen at the aft outlet of my rear engine has square holes about 1/2 inch in size. I wonder is you could add an additional screen with smaller openings that wouldn't let even a small bolt through? What might be the pros and cons of that idea?

[Paul Sharp]

Gonna post a reply to my own questions. I talked to the shop that O/H'd my front engine back when I bought the plane (good shop with lots of experience with Skymasters - more than any other I know of). They have the actual material that the screens are made of. They are going to send me some and the price is right. So I'm replacing what I have with the correct stuff (what I have is galvanized and this stuff is stainless steel). The guy tells me that the holes are about 1/4" in size instead of the 1/2" that's on mine.

So for those of us with the earlier models, there's some input on that question...