Mandatory Service Bulletin: Inspection and/or replacement of expansion tank assy. for ROTAX® 912, 914, 912 i, 915 i and 916 i (Series) Aircraft Engines

Im just trying to understand so please excuse my ignorance. The SB says  my engine was delivered  with expansion tank part# 922666 or 922668. I have a new never flown engine so I would assume I have one of those part # tanks as my SN falls in the range of effected engines. Looking at my tank, the sticker on the side says 622051. That part number does not come up in the IPC. If I were to order a part would I order 622051 or 922668?

Because I dont have 922668 does that mean someone has worked on my engine? Its new so thats why I am confused.

Expansion tanks with a sticker labeled P/N 622051 OR 622050, located on the side of the tank, may correspond to Rotax P/N 922 666 or 922 668, which are affected by this Service Bulletin (SB).

The sticker number alone cannot be relied upon to accurately identify the correct part number for the affected coolant expansion tanks. If your engine serial number (S/N) is listed in the SB document (certified or non-certified), you must inspect the expansion tank and replace it if necessary.

It seems that I got lucky. Intending to replace my ~2005 OEM tank (thin pipe walls, no inspection glass) at the next rubber change, I ordered a replacement from LEAF 2-3 years ago, presently sitting on a basement shelf. While it came in a bag labeled 922666, the tank is marked "VE 22536-0, 622050, 174/07/2022". But poking around with a borescope, it seems that a couple internal pipes are quite badly aligned with the wall openings. Should I fret about this, or is it normal?

Hi there.

I have checked my expansion tank number, and it is 622051, so I assume I don't need to check either?

Chris

Expansion tanks with a sticker labeled P/N 622051 OR 622050, located on the side of the tank, may correspond to Rotax P/N 922 666 or 922 668, which are affected by this Service Bulletin (SB). Please note that the sticker number alone cannot be relied upon to accurately identify the correct part number for the affected coolant expansion tanks. If your engine serial number (S/N) is listed in the SB document (certified or non-certified), you must inspect the expansion tank and replace it if necessary. (See attached photos for reference.)

Identifying Weld Quality:

We understand that many individuals may find it challenging to distinguish between a good and proper weld versus a bad one.

• Good Weld: Consistent and uniform around the entire connection port.
• Bad Weld: Inconsistent or missing sections around the connection port.

At this time, we do not have additional photos to illustrate what a bad weld looks like beyond those included in the SB. However, we have edited the photo provided in the SB to better highlight the characteristics of a bad weld. (See attached photos.)

 Clarification About Tack Welds:

Some have raised concerns regarding the weld blob at the top of the port. Please note that this is a tack weld and is considered normal. The primary concern should be any missing welds around the edges of the port hole. In the attached photo, the dark spots around the circumference of the port indicate missing welds, which are considered unacceptable.

Recommendation:

If you are uncertain about the condition of the welds on your tank, we strongly recommend replacing it with a new one. Remember: When in doubt, swap it out.