Brakes work? Yes and no.

[Rich]

The guy I use for my flight reviews mentioned he was giving a flight review to another Diamond owner and discovered the copilot side had no brakes, though the pilot side was fine. Turns out the brake fluid reservoirs were exhausted. Since we're doing a FR next week, I thought I'd confirm that my copilot side worked. Answer: No. Who checks, right?

So we need to rectify in the next few days.

[smoss]

Even when the reservoirs are filled appropriately (which is not all the way to the top), the copilot side brakes on mine often over time get "squishy", presumably air bubbles get in that side somehow. A few hard pumps on the those brakes and they return to normal.

[Steve]

Actually, I do check the fluid levels every annual, although they never seem to change much in between. When I fly with my son, I have him do the brake check in the Taxi Checklist from the copilot's side as well as mine from the Pilot's side.

[blsewardjr]

We repaired a leak in my co-pilot's brake at my last annual by tightening the fluid reservoir by one turn. My re-furbisher discovered it when putting in a new carpet.

[Rich]

We repaired a leak in my co-pilot's brake at my last annual by tightening the fluid reservoir by one turn. My re-furbisher discovered it when putting in a new carpet.

This could be a culprit, but both left and right pilot side toe brakes are the same non working. But we'll check into it. No obvious carpet stains, though/

[Rich]

So, more diagnostics today. Confusion reigns. Data points:

1. Both reservoirs contained the correct amount of hydraulic fluid. I made a specialized dipstick from a zip tie to measure.
2. One of the caps had no vent hole. Now they both do.
3. I sat in the copilot's seat for awhile and pumped and pumped. The brakes now seem to work from that side, though there's a bit more travel than on the pilot side. Fluid levels are down a bit from what they were, but still within or at limits.
4. The copilot side brakes don't seem particularly spongy, but there is substantial opportunity for air bubbles to lurk in the lines between the left and right side. So I figure we'll wind up bleeding the system.
5. Both left and right brake pedals on the copilot side have the same feel and amount of travel.

[Chris]

Sounds similar to the problem reported by Lance in this old thread.

[Tim H]

I had the same issue that I discovered when I stared to work on my CFII and flew from the right seat. Bleeding the brakes solved the problem.

Tim

[Rich]

After doing nothing but lots of pumping away on the starboard side these brakes work pretty well, with a wee bit of sponginess. And fluid did draw down from the reservoirs in the process. So we'll go ahead and bleed the system at annual next month.

Current conclusion: It's disuse of the starboard side brake pedals that causes air to be ingested over time into the system. If enough air gets pumped in, it will get into the lines that feed from the starboard side to the port.

In the long term, I'll make sure the starboard brake pedals get pumped from time to time.

[Colin]

Probably a good thing to add to my thirty day checklist (VOR, FIKI test, Plexus polish). It happened on the DA40 when I first got it. There was a leak, and after that was fixed it didn't seem to remain an issue, but I had a CFII on that side often enough for the first couple years.