Airplane Owner Maintenance

A Maintenance Oriented Podcast For Airplane Owners, Pilots, and Mechanics

Tag: vacuumsystem

157 – Valve lapping, shock mounts, and vacuum issues

October 17, 2020 / / 0 Comments

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Valve lapping is sometimes a great option for improving cylinder compression and extending the life of an exhaust valve. We’ll talk about it in today’s episode.

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In today’s episode, we have three issues from Trace’s Cessna 310 this past week:

  1. Lapping an exhaust valve.
  2. Repositioning and correctly installing an engine shock mount.
  3. Evaluating a vacuum system issue, and making a plan.

First, the lapping project. At the recent annual inspection, the compression in the right engine cylinder #4 was in the mid-50’s. After lapping we got a solid 64/80, a significant improvement.

Second, one engine shock mount was out of position:

The 1/4 inch gap got my attention and we had to hoist the engine and loosen the bolt to install the lower shock mount correctly. Here’s the result – notice the 1/4 inch gap has been closed.

The third isssue showed up when we ran the engines. Notice the oil pressure gauges… only the left engine is running. But the vacuum gauge indicates both vacuum pumps are operating.

This usually indicates a problem with the vacuum manifold valve. Most likely, it will need to be replaced.

After we checked and verified there were no oil leaks, Trace took me for a ride in his Cessna 310… a great experience! Thank you Trace!

Trace has been a Navy F-18 test pilot for quite a few years, and it was awesome to fly with him!

And to wrap us this episode, I also met Tobin this past week, owner of a very nice Piper Cherokee Six. He dropped his airplane off at SHD for his annual inspection. Hopefully I can give an update in the future about how his inspection turns out.

Trace, and Tobin, it was a pleasure to meet both of you this past week!

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156 – The Weirdest Vacuum System Problem I’ve Ever Seen

October 5, 2020 / / 0 Comments

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Although a shop vac might not pull as much vacuum as an engine driven vacuum pump, it can still be useful for some parts of the troubleshooting process. This was just one thing we did on the path to solving a very strange vacuum problem. Listen to the story in today’s podcast episode.

Our sponsor for this episode is PilotWorkshops.com

Regardless of where you are in your aviation journey, PilotWorkshops has the perfect resources to help you become a safer and more proficient pilot.

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And finally, be sure to check out the newly released book, “Airplane Engines: A Pilot-Friendly Manual.” It’s packed full of useful information that’s easy to understand. For example, you can learn about doing an in-flight ignition check, or even an in-flight induction leak check, and so much more. Click here for more information.

Now for today’s episode… we’re featuring two squawks on a twin Cessna.

Squawk #1: The left fuel gauge was completely inoperative, both for the main tank and the aux tank.

In this episode, we talk about the troubleshooting process that led to changing the fuel quantity indicator. The gauge from eBay worked great, and the system was back to normal.

Squawk #2: The vacuum system had a weird problem… the vacuum gauge showed that both vacuum pumps were functioning, but the vacuum was very low (approx. 1 inch of Hg instead of 5 inches.) Apparently it doesn’t take much vacuum to pull the inop indicator in (the little red button for the left and right vacuum pumps in the vacuum gauge.) This squawk was challenging! Actually, the solution turned out to be simple, but the discovery process was not so simple.

We checked an extensive list of components, both in the vacuum system and in the surface deice system, since the two are inter-related, and the squawk had two parts: the vacuum indication was very low, and the wing deice boots were not being pulled firmly against the surface of the wing (which requires good vacuum.)

Here’s the deice valve in the right engine compartment, one of the components we tested in this process.

Thankfully, we did not end up ordering any high-priced components in this scenario, because the solution turned out to be very simple… we removed an elbow between two vacuum hoses, and installed plugs in them instead. Listen to the audio for the details.

Reminder: the video training course for “Servicing Landing Gear Shock Struts” will be coming soon… be watching for more details.

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