Airplane Owner Maintenance

A Maintenance Oriented Podcast For Airplane Owners

Month: November 2016

042 – If the Reservoir is Empty, There’s Probably a Good Explanation!

I recently did an annual inspection on a Mooney M20J, and when I checked the brake fluid level, the reservoir was empty.









In this airplane, the brake fluid reservoir is inside a panel on the left side of the airplane, behind the left wing.









When I did the inspection, I noticed the parking brake valve had a little fluid on it, but it did not seem to be leaking enough to account for an empty fluid reservoir.  So I filled the reservoir and continued on with the inspection and repairs.

But when I was ready to reinstall the belly panel, I had this feeling that maybe I should double check that parking brake valve.  So I applied the brakes and set the parking brake.  And within a short amount of time, there was a significant puddle on the floor under the airplane.img_4399







So, I had to remove the parking brake valve, put some new o-ring seals in it, and reinstall it.  After that, the system worked fine without any leaks.img_4397







This scenario reminded me of some other times where I’ve had brake fluid leaks, and what the problem turned out to be.  Listen to this podcast episode to hear about those stories.

Bottom line:  If your brake fluid reservoir is empty, or much lower than normal, it might be time to dig a little deeper to try to find any leaks that might be happening.  After all, you don’t want to be surprised with having no brakes available at just the wrong time!

So, I’d recommend that you check your brake fluid yourself occasionally throughout the year… get some help if you need it… don’t be caught with an empty brake reservoir!

Thank you for listening to Airplane Owner Maintenance!  If you have not left a rating and review for the podcast, please go to iTunes and do that… I would be so grateful!

And speaking of being grateful, I hope you’ve had some time to think about the things you are grateful for, this Thanksgiving Season.

For me, I’m first of all grateful to God… and specifically as it relates to this episode, I’m grateful for the times he prompts me to think about things that need attention, like this parking brake valve… things I might otherwise overlook… after all, I was just about ready to put that belly panel back on…

And secondly, I’m grateful for all of you… you who listen to the podcast, and especially those of you who have contacted me and shared your thoughts with me.  I always love to hear what’s going on out there in the world of General Aviation, especially the PEOPLE who fly and work on the airplanes!

So Happy Thanksgiving, my aviation friends!


041 – What in the World is an Airworthiness Limitation?



Any idea what that red switch is?  This airplane is a Diamond DA-40 with a Garmin G-1000 system.  The red switch is for activating the emergency battery power for the attitude indicator to the right of the airspeed indicator.







The battery pack is mounted behind the copilot’s instrument panel, and it must be changed every 2 years, as required by an “Airworthiness Limitation” in the DA-40 maintenance manual.  This is not optional, but mandatory.




So, what is an “Airworthiness Limitation?”

It is an FAA approved requirement for maintaining the airworthiness of an airplane.

Check out this website to see some good information regarding recommended vs. mandatory:

91.403(c) No person may operate an aircraft for which a manufacturer’s maintenance manual or instructions for continued airworthiness has been issued that contains an Airworthiness Limitations section unless the mandatory replacement times, inspection intervals, and related procedures specified in that section … have been complied with.

Some other items on this Diamond DA-40 that are affected by “Airworthiness Limitations” are:

Garmin G1000 system as installed in the DA-40:  Mandatory replacement of the 5 slow blow fuses in the system, as well as some other specific checks of the flap and autopilot system.

Powerflow Exhaust System:  Mandatory lubrication of the slip joints every year, which requires removal of the exhaust system.

AmSafe Inflatable Seatbelts:  Mandatory system checks, and replacement of the inflators and the EMA (Electronic Module Assembly.)

These previous 3 items are not in the Chapter 4 Airworthiness Limitations section of the Diamond Maintenance manual.  But rather, they are in the specific ICA documents for these components.

So, this is one example of how important it is to be familiar with the ICA’s for the modifications in your airplane.

How about your airplane?  Are all the “Airworthiness Limitations” being complied with?

Listen to today’s episode for more information.

Hey, one more thing… If you haven’t left a rating and review in iTunes for this podcast, could you take a minute and do that?  I would be so grateful!