Letters

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Engine Assembly Sealants and Lubricants

I enjoyed Dave Prizio’s article, “Choosing the Right Sealant” [“Best Practices,” May 2016]. I have a Glasair with a Lycoming O-320 and need to take off the accessory case to get to the oil pump. I can’t seem to find in the Lycoming manuals what to use to seal the case and what to pre-lube the oil pump with. It seems like every mechanic has some special concoction of STP and mineral oil to pre-lube items. Do you know of a chart with current sealants or assembly lubes that can be used in different areas of the engine? If there is such a document, please point me in that direction.

–Kevin Sublett

Dave Prizio responds: Whenever you are dealing with a certificated product such as an engine or propeller, you should always look to the manufacturer’s service instructions for the answers to your questions. The FAA requires that these items have such instructions readily available as part of the certification process. No matter what any “expert” mechanic tells you, there is no guesswork or magic involved in getting the answers you need regarding repair, maintenance, and overhaul procedures or recommended products. If you can’t find the needed information online, call the manufacturer’s technical support line and ask for it.

To answer your specific question about assembly lubricants, I refer you to the Overhaul Manual and Lycoming Service Instruction 1059. A mix of 15% STP and 85% 50-weight oil would be good for your reassembly of the oil pump. This recommendation can be found in section 3-39 of the Overhaul Manual. For other assembly lubricants, see the previously mentioned service instruction.

Jim Bede Sr.

Amy Laboda’s article on Jim Bede Sr. [“Promises, Promises,” April 2016] was a refreshing departure from the usual articles written about him. She outlined his own losses in relation to the BD-5 program, something that is usually missing in other articles on the same subject.

Airshow coverage sponsor:

There are some additional figures on the BD-5 that might interest your readers. Two of the most significant ones are the sad fact that only 200 BD-5s were ever finished and flown out of the 5000 kits sold. Many of those were flown for a relatively short period of time and then donated to museums. The second figure of over 6500 line numbers sold for the production BD-5D is seldom mentioned. Sadly, not one BD-5D was ever built. Amy also mentioned that Jim worked for North American Aviation, but he didn’t work on the F-4 Phantom at NAA; it was a McDonnell design.

–John K. Lewis

TruTrak ECO

The “ECO-nomical Autopilot” article [May 2016] is a dandy. I really like things that are different, elegant, and economical. This is a really cool idea. But won’t it mess up a carefully balanced aileron?

–Roger Laubhan

At the time we flew the ECO, the installation documentation had not yet been finished, so we didn’t have a chance to review it. In checking with TruTrak, they specifically call out the need for rebalancing control surfaces after the addition of the ECO servos and tabs.—Ed.


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