Next week I am flying to an airport and going to have dinner. But I've never stepped out of my aircraft except at my home airport!
When I park on their ramp, do I keep the parking brake on?
$\begingroup$
$\endgroup$
5
-
2$\begingroup$ do you want a runaway plane? $\endgroup$– ratchet freakJul 17, 2015 at 19:11
-
$\begingroup$ At my home airport, it's forbidden to set the parking brake. But what if they try to move it while the brake is on? $\endgroup$– flyinghighJul 17, 2015 at 19:12
-
1$\begingroup$ call ahead and find out. Or ask the tower (if there is one) after you land. If there isn't then check with the guys on the ground. $\endgroup$– ratchet freakJul 17, 2015 at 19:13
-
$\begingroup$ Great idea! Thanks. I figure if there are tie downs, you likely don't need the brake; otherwise yes? $\endgroup$– flyinghighJul 17, 2015 at 19:15
-
5$\begingroup$ get yourself a set of chocks and use those $\endgroup$– rbpJul 17, 2015 at 19:50
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
6
I assume you're talking about a light GA airplane (Cessna/Piper singles or twins).
The short answer is "Maybe, but you probably shouldn't.": The parking brake should only be used for as long as necessary to get wheel chocks in, and should then be released.
Aside from making it inconvenient for the local ramp personnel if they need to move/tow your plane, setting the parking brake has a few other downsides which are related to the way the parking brakes work on your typical light aircraft.
When you set the parking brake you're doing two things:
- You are pressurizing the hydraulic lines that run to the plane's brakes.
- You are doing something to prevent that pressure from bleeding back out.
(Exactly how you accomplish this varies depending on the plane - the "parking brake" on a Piper Cherokee is a tab that prevents the brake handle from returning to the "released" position, maintaining pressure in the cylinder. I think the Cessna 150 pressurizes and then turns a valve.)
Because of how the parking brake works it has two common failure modes when it's set: Pressure can bleed out or it can blow out.
Bleeding Out happens because fittings, seals, hoses, etc. in the brake system aren't perfect. Hydraulic fluid will escape past whatever little opening it can find, and eventually there will be insufficient pressure in the system to keep the aircraft from moving.
If you happened to be parked on an incline steep enough to get the plane rolling it will then go off on its own down the hill just as if you hadn't set the brake (and you will be very confused when you get back to where you left it).
Blowing Out typically happens on hot summer days when there aren't many little openings for pressure to leak out through: 5606 Hydraulic Oil (the stuff in the brake lines) expands as it gets warm, and with the parking brake set it doesn't have anywhere to go (it can't get back to the main brake reservoir). If you land at 11:00 (local time), set the parking brake, and go have a nice leisurely lunch there is a good chance that when you return to the plane at 13:00 or 14:00 you will find that the hydraulic fluid in your brake system has blown out of whatever the weakest point in the system is (often the seals on the toe brake cylinders, sometimes around the calipers, occasionally a hose fitting fails).
This means you're going to have a mess of hydraulic fluid to clean up at best, and at worst if you're on a hill you're in the same situation as above (the plane has gone rolling away), only now there's hydraulic fluid all over as well (sometimes in a little red trail to wherever the plane has wound up).
So bottom line: Try to avoid leaving the parking brake set for extended periods of time, especially if there might be a temperature increase while it's set.
Instead bring your chocks with you (if you own your own plane, or even if you're a renter, pick up a set of "travel chocks" - they're right at or just under 1 pound, you won't even notice them) and chock your wheels when you leave the plane. Ramp personnel will be able to spot the chock easily, and they're unlikely to fail.
Ideally you would also tie the aircraft down if possible, but some ramps don't have tiedowns (and others are bring-your-own-rope).
answered Jul 17, 2015 at 19:42
-
$\begingroup$ Man! So there's no way around asking. I should pick up my own chocks though...Great info, thanks. $\endgroup$ Jul 17, 2015 at 19:48
-
$\begingroup$ That's very interesting about the hydraulic issues, I never thought about that. But in the end the brakes are there for a reason so I guess it comes down to whether - for your particular aircraft - the risk of a failure is important compared to the risk of the aircraft moving. The C172S POH, for example, says to keep them set whenever the aircraft is parked. $\endgroup$– PondlifeJul 17, 2015 at 19:52
-
$\begingroup$ A lot of airports have chocks available, but I've been to a good number that don't (or they have to go hunt for them) so I just throw a set in the plane if I know I'll be on the ground longer than it takes to dump fuel inthe tanks & leave. There are cheaper chocks (or you can even make your own), but I like the Travel Chocks: they're study enough that I use them as my primary tiedown chock. $\endgroup$– voretaq7Jul 17, 2015 at 19:52
-
2$\begingroup$ @Pondlife Interestingly I've never seen a Cessna blow out its brake system - I've seen Warriors sitting in a puddle of hydraulic fluid because the fittings at the wheel gave out when it got warm though. (Piper is mute on the subject, at least in my manual: They tell you there's a parking brake, but nothing about when to use it.) $\endgroup$– voretaq7Jul 17, 2015 at 19:57
-
4$\begingroup$ Honestly, 'parking brake' is a total misnomer for these. 'Single point brake application lever' is more accurate. $\endgroup$– egidJul 17, 2015 at 22:13
$\begingroup$
$\endgroup$
The only (?) downside to setting the parking brake on is that no one can move the aircraft around if they have to (unless you leave it unlocked too). So if you're leaving it somewhere where other people may need to move it without you, you should leave it off.
Lots of FBOs will move your aircraft without you for good reasons: to make room for other aircraft, to fuel it, to put it in a hangar, protect it from bad weather, move it out of strong wind and so on. You can just check with the FBO staff what they prefer, assuming there is an FBO there, of course.
If there's no FBO then the best option is probably to tie down the aircraft in case the wind picks up, with the parking brake on. If there are no tie downs then you really have to leave the brake on because otherwise there's nothing at all stopping the aircraft from moving. And if you regularly fly places with no FBOs and no tie downs then you should probably consider bringing your own.
answered Jul 17, 2015 at 19:25