Repairing a leaking oil pan

[lowNslow]

Randy Selchert, of Ajax Welding Inc., 319 Wolf Rd., San Antonio, TX 78216 800/531-7272 or 210/342-9494 tells me they not only weld these magnesium sumps, they are an FAA Certified Repair Station, and usually have at least one in stock for exchange.
He said that the only way to properly repair these is to thoroughly clean them (they are porous and absorb oil) then weld a patch on the outside of the unit where the weld won't be weakened by inbedded oil. The average price of such a repair is $500. They been in business as certified aircraft and crankcase welders for many years. They're located just off the SAT Int'l airport.

I sent my sump to Ajax for repair about a month ago, just got it back yesterday. The sump had been repaired by Drake when I had the engine overhauled about 4 years ago, and recently developed a crack just forward of the carb where it had been welded.
The new repair is external with a patch that runs almost the full width of the bottom of the pan and goes forward around the forward drain plug. Looks like a good job, BUT even tho I sent the sump to Ajax, it turns out they send to someone else, you guessed it - Drake. Hope this one does the job.

[N3243A]

My engine overhualer just sent my sump to Drake Air in Tulsa for welding but after re-reading this thread I am very tempted to have them stop work. After reading of several experiences here it looks like the weld repair looks good but sets up stresses in the sump that later lead to cracking and subsequent oil loss. Not a good thing to happen when your over Prince William Sound on the way to Cordova....Or in the "Trench" on the way to Kelowna, BC. Anybody have any more input on Drake Air or sump welding in general?

My sump is actually not too bad in that there are a few pits that are about 1/2 way thru the sump wall. I'm tempted to just clean 'em up and use the best epoxy I can find.

Bruce

[alaskan99669]

Working on my annual and my mechanic found the source of an annoying oil leak that has plagued my aircraft. Turns out the oil sump had three hairline cracks that are invisible to the naked eye but slowly materialize when the case is dried with brake clean and you wait a few minutes for the oil to begin seeping out. And of course the only way to clean and inspect properly is to remove the cowling and the shroud just below the oil sump. I tried calling Ajax (which a post above says they farm out work to Drake), but their number has been disconnected. I called Fred at Okanagan Aero Engines and confirmed previous posts that they only epoxy non-welded sumps. I called Drake and left a voice mail, but my call was never returned. I entered the part number (530763) online and found Preferred Airparts (http://www.preferredairparts.com/) had two yellow tagged repaired ready to ship. I filled out their online quote request and was quoted $795 + $150 core charge. Still no word from Drake so I placed the order online as I was leaving town for a week. Came back home a week later and found the sump delivered with a repair from 8130-3 from Drake Air inc. Shipping was another $50 for Fed Ex to Alaska. It comes with a 30 day replacement guarantee which I guess is better than nothing. It also came with clear instructions for receiving core charge credit.

Now for some pictures...
(Click on pictures to enlarge to read text)

[GAHorn]

Corey, THANKS for the excellent photos and descriptions! Your old (defective) weld repair: Do you know who actually did that work and was it an approved repair? Do your logs give you that info?

[alaskan99669]

Corey, THANKS for the excellent photos and descriptions! Your old (defective) weld repair: Do you know who actually did that work and was it an approved repair? Do your logs give you that info?

Actually I do. My logs indicate the engine underwent a top overhaul that began December 1976 with 2000 hours TT, 1580 hours SOH. It has an entry that says "sump welded to fill corrosion holes" and has a yellow tag from Bolduc Aviation Service, Crystal Airport, Minneapolis, Minnesota that says "Fill corrosion holes inside."
The engine was disassembled again in April of 1999 for a complete overhaul. It says the sump, case, and accessory case were cleaned and inspected (3038 hours TT).

[GAHorn]

That's excellent! May I suggest you contact your FSDO and encourage your AMT (Aviation Maintenance Technician, A&P etc) to file a M or D report? (Form 8010-4) Do not ship your defective case back as a core (I doubt they'd accept it anyway since it has a defective previous repair...you'll only lose your sump and your core charge will apply anyway.)

The reason it's a good idea to submit a Form 8010-4 is to alert others as well as to cause FAA to investigate the welding practices of Bolduc and determine if they actually have the authority/approval/capability to weld or make such repairs. You could be saving someone else's skin, or you could be contributing towards improving repair practices.

[alaskan99669]

Too late. I just got back from the P.O. But I will talk to my AMT about submitting that form with pictures if need be. I almost kept the case bucause I knew it would cost about $50 to ship out and probably is not repairable but then I figured if they could repair it then another 170 may be easier saved.

[GAHorn]

The only reason I suggested you not (yet) send the case in.... was in-case the FSDO needed to examine it for the M/D report.

I once flew an airplane whose annual inspections had been pencil-whipped by a CRS for at least 4 years, and they'd signed off the Cessna inspection forms claiming they'd inspected the wing attach fittings each year.

When by chance, we had occasion to look into that area, we found the fairings had not been removed since the last paint job 7 years previously, which meant those fittings had not been looked at for at least that long. When we saw the fittings...they were almost completely destroyed with intergranular corrosion.

I instructed the shop not to lose those, as we intended to take action against the pencil-whipping-shop. Unfortunately, the right-hand didn't talk to the left-hand at that shop and the defective fittings had been sent out of state for the purpose of satisfying someone else's curiosity. This prevented our FSDO and our legal from pursueing a fraudulent shop who remained in business for another 10 years (before they finally went bankrupt.) We'll never know who all they may have injured financially or physically while they cont'd to do their business.

[jrenwick]

...The reason it's a good idea to submit a Form 8010-4 is to alert others as well as to cause FAA to investigate the welding practices of Bolduc and determine if they actually have the authority/approval/capability to weld or make such repairs. You could be saving someone else's skin, or you could be contributing towards improving repair practices.

I had occasion today to visit Bolduc Aviation Specialized Services at Anoka County Airport, Blaine, MN, owned by Darrell Bolduc. They're an engine shop with an excellent reputation, and I've done lots of business with them in the past. I showed this thread to Kevin, one of their senior mechanics, who said that they don't do any magnesium welding in-house because they're not equipped for it, and the very high likelihood of cracks developing after welding.

However, he said, Darrell's father had a welding shop in Crystal, MN, until some time in the late '70s, and that was probably where the welding on Corey's oil pan was done. That might have been 35 years ago or more, and if so, I'd say that weld held up pretty well!

Anyway, the guys at Bolduc don't deserve to have any asparagus cast on them over this, it seems.

Best Regards,

John

[GAHorn]

The intent is not to cause Bolduc a headache with FAA. It's to assure that if any/many other sumps were so-repaired by them, ...regardless of how long ago.... that the flying public be notified that questionable repairs exist and that owner/operators should check their records to determine if sumps have previously been repaired/supplied by that shop. It'd be a shame if we knew about this past practice...and someone else should suffer a preventable accident simply because no one wanted to report the malfunction/defect.

[GAHorn]

I am in receipt of a letter (pdf) from Mr. Darrell E. Bolduc, President of Bolduc Aviation Specialized Services, Inc. (no contact info or letterhead provided other than the return email address, presumeably that of his secy)

The letter explains that his father owned "Bolduc Aviation Service" from 1952 to 1977 and then sold the company. He also indicated that his father welded the subject (now cracked) sump in 1976 and stated his father had " the authority/approval and capability" to make such welding repairs, as it was an "FAA approved welding repair station". (The "yellow tag" should indicate that.)

Darrell Bolduc further opines that if the engine was subsequently overhauled by another approximately 15 years after the weld repair and that the sump was not "cracked at this time" .. and that "In 2010, 34 years later, the sump cracked." and further "If they can get 34 years of good service (and an overhaul) from the welded repair, consider that repair to be a success - period."

Mr. Bolduc also recommended that "anyone who needs their sump repaired to send it an FAA approved welding repair station."

I don't disagree. (I also still believe an FAA Form 8010-4 submission is appropriate.)

I'm glad Mr. Bolduc had his secy write me to clarify the difference between his deceased father's former company and the present company of a similar name, presided over by Darrell E. Bolduc, "Bolduc Aviation Specialized Services, Inc."

I've suggested to him to supply a copy of his letter in a different format and I would post it in it's entirety.
(current format has some personal contact info (mine) not suitable for this forum)

[Bruce Fenstermacher]

I think after learning more of the history and time frame of this repair that I would also consider it to be a successful repair. After all it lasted at least as long as the life of the original sump prior to its repair.

I think that the message here is that IMHO, a welded repair of these sumps, no matter who did it, is subject to cracks at some point and periodic inspection would be indicated.

Also given the time frame in years between overhauls where internal inspection can take place, it might be just as likely a unrepaired sump would spring a leak as a sump repaired using the best technique. I also think an unrepaired sump springing a leak due to corrosion has a much higher chance of springing a leak that would lead to a catistrophic failure due to oil loss, than a crack from a weld repair which is likely to only lead to a seeping crack.

I'm glad John had the opportunity to visit with Bolduc and John and Bolduc took the time to respond. There are so many things we can now find and read on the web to support any argument while rarely being informed of the full story. My opinion of Bolduc was not swayed one way or another based on this report and I do not think that was the intent from any party. Personally I'd rather be eating that freshly cut asparagus than cast it on any person or company.

[GAHorn]

I'm impressed that the welded area did not suffer the corrosion-damage the original sump apparently suffered. I personally am more inclined towards a weld-repair than an epoxy-repair, because I believe corrosion can continue beneath epoxy, and epoxy might be subject to shaking loose and circulating in the oil.

It might be appropriate to anneal any welded sumps to alleviate thermal stress which likely leads to the cracking. But being only a shade-tree gorilla-welder, I do not have any special expertise in welding of any kind, much less magnesium.

Does anyone with metals/casting-experience have input as to why this sump was made of magnesium instead of aluminum? (I take it mag has greater tensile strength?)

[jrenwick]

...It might be appropriate to anneal any welded sumps to alleviate thermal stress which likely leads to the cracking. But being only a shade-tree gorilla-welder, I do not have any special expertise in welding of any kind, much less magnesium....

I've heard people on this subject saying that in order to weld magnesium successfully, you have to be able to raise the whole piece almost to welding temperature before welding. In an inert atmosphere, of course. I'm just repeating what I've heard -- I know a lot less about welding than most of the rest of you!

[c170b53]

The repairs I've seen, the pieces were placed in strictly controlled ovens, heated, removed, welded, placed back in the ovens to control temps and cool down time. I don't know at what temp the piece was raised to before welding and unfortunately all that expertise has been done away with in the name of unlocking shareholder value. Some of us really know what that means.