Brake check
Posted by 1E-12@reddit | flying | View on Reddit | 71 comments
Just recently heard of someone who checks their left and right brakes independently before taxi (like: Roll -> stop with left brake. Roll -> stop with right brake).
Does anyone else on here do this? It never even occurred to me but it makes sense.
Prefect_99@reddit
No need to come to a stop imho. Before you move off proper you should check the brakes can bring the aircraft to a stop a low speed. You should notice if equal pressure produces a non symmetric response. The idea being you can immediately pull the mixture to shutdown if they do not and you'll be moving slowly.
Then check fully free steering as you move off again.
Once clear of dispersal or if safe you can just independently check each brake to check it pulls to the correct side. Doesn't need to be to a stop (you've checked you can manage that).
poisonandtheremedy@reddit
I do, every time at the start of my roll from parked. Just get it rolling, brake check (both at same time), then I get rolling again and do a full left rudder turn and full right rudder turn. On a PA-28 the nosewheel is directly connected to the rudder so I ensure I have full rudder pedal movement both directions. Then I continue my taxi as normal. This all takes about 6 seconds.
gearheadstu@reddit
I’m pre-solo in a 172, and my CFI has instilled this habit in me.
That said, it isn’t super fruitful. I’ve had to reject a flight once when, upon attempting the turn from taxiway to the hold-short area, it was clear that one brake wasn’t up to snuff. The check prior to taxiing didn’t show off the problem.
Quantum_Aurora@reddit
The only benefit is that you'd notice the problem sooner if there was a problem with one of them.
You'll notice a brake not working during engine run-up.
anonymous4071@reddit
If you checked both simultaneously would you not notice a failed brake by asymmetric braking?
1E-12@reddit (OP)
I kinda thought the same thing, but maybe because your moving so slow during brake check might not even notice. Just brake check at 10+ kts lol.
Shabado52@reddit
I check left, right, then together on the initial roll
butiamnotadoc@reddit
you 10 kts may be an exaggeration but I did some 182 recurrent training with a guy who had a failure and I have adopted his practice and do a test immediately on rolling after start followed by a second going a little faster. Maybe more wear but that first test isn't asking a lot of brakes. Testing asymmetrically seems like a reasonable idea.
1E-12@reddit (OP)
Oh neat like a brake check for your brake check.
Yes I was exaggerating but your method makes sense.
AlotaFajita@reddit
I’m not satisfied till the 5th or 6th brake check. More brake failures occur during week days than weekends, so I’ll do 7 - 8 during a week day. This really cuts into my training time and my instructor hates it, but you never know. I gotta run, time for another brake check.
1E-12@reddit (OP)
You do brake check before your clearing turns too, right? Wouldn't want to find out your brakes doing work when you spot head on traffic at the same altitude.
anonymous4071@reddit
Now in all fairness, on the 220 we have an MEL procedure for brake redundancy loss that has us check both sides independently. but that’s not done in motion so who knows
1E-12@reddit (OP)
Interesting, like you step on each pedal before you start moving?
anonymous4071@reddit
At the gate during our preflight with the chocks in, parking brake off, captain checks left and right,fo checks left and right, alternate braking on, rinse and repeat the test, alternate braking off, parking brake on. no abnormal indications and proper brake function and we’re good to go. fun fact, the A220 brakes are electric, not hydraulic
f1racer328@reddit
Are you saying brake by wire, or the actuators are electric?
roguemenace@reddit
Electric actuator with no hydraulic backup. It's called the EBrake if you want to look it up.
1E-12@reddit (OP)
Brake-by-wire, neat
AK_Dude69@reddit
I do it on my 182, but I have big tires so it’s more a practical thing to keep moving.
Plus_Goose3824@reddit
Having flown in a single engine airplane with a chronic issue of a brake going soft, I can say that you'll know when just one isn't working adequately. If you turn as you come to a stop, they aren't working evenly. It wouldn't hurt to be more precise and test them separately, but if I can come to a firm stop on the ground and maintain direction, then why bother to test them individually?
DudeSchlong@reddit
Yes because I had a brake failure when I was taxiing and didn’t notice because I didn’t test independently
FridayMcNight@reddit
Doesn’t make sense to me. The brakes are mostly independent systems. If you press both pedals at the same time, you are still testing them independently, just at the same time. There’s no evident benefit to testing right and left at different moments in time. If one of the brakes is failing, you’ll notice it regardless of when you press the pedal.
LateralThinkerer@reddit
For an aircraft with a parking brake that just pressurizes both won't you notice it pretty quickly on runup?
1E-12@reddit (OP)
Only time I ever touch the parking brake lever is to make sure the last person didn't engage it.
LateralThinkerer@reddit
True. I use my feet as well as the parking brake but the principle is the same.
1E-12@reddit (OP)
Oh I totally missed the point. Classic fixation on the part you don't agree with and ignore the point of the response. You're right even with my feet holding the brakes 1700 RPM should make the plane turn.
On the other hand this thread has made me think that brake check should be more of a "stress test" rather than a light tap. I'm thinking it might be better to give the pedals a nice firm step before walkaround and feel for good pressure. Not like 200 lbs force but basically simulate hard braking and hold a couple seconds. If you have a leak you should be able to feel it or feel the pedals continue to sink as you hold pressure. This also might exaggerate any external leaks making them easier to spot (if they are in an area that is visible during walkaround).
LateralThinkerer@reddit
My instructor watched me set the brake and then do the startup and she asked "what happens if that lets go when the engine starts?" Looking at Piper's well-worn finest effort convinced me to keep my feet on the pedals so I didn't launch into the cornfields.
1E-12@reddit (OP)
Yep once you know what it feels like it's pretty easy to spot!
GingerB237@reddit
Even Civil Air Patrol who is super strict on checklists and checking every little thing does not check them independently. On a taildragger you’d definitely notice the asymmetric braking. Not sure on a 172 or other nose wheel aircraft.
SpartanDoubleZero@reddit
I do a quick tap on left to make sure I swing left, then right, then both, taxi off the apron and off to the side to get the weather, get taxi clearance and get ready to boogie.
KosmolineLicker@reddit
I teach this way.
After a left master had a brake fluid bypass and a student attempting to taxi off the runway being unable to make the turn and me having to slam on the right brake to keep it from going into the grass, lesson learned.
Should you catch it with both? Maybe, if you're going fast enough. But slow checks are harder to detect.
IdahoAirplanes@reddit
In a taildragger … absolutely and also on final.
spectrumero@reddit
Unless you have a tailwheel that locks, you don't need to check one then the other - if you press both brakes at the same time and one isn't effective, the aircraft will begin to turn and you can tell instantly.
1E-12@reddit (OP)
Thanks - Why specifically in a taildragger? (I've never been in one but I guess it might be because directional control is harder on the ground?)
Also how do you check in the air? Just feel for resistance in the pedals?
IdahoAirplanes@reddit
If one brake works and the other doesn’t unexpectedly then you are in for a wild ride called a ground loop. In the air you just check for resistance.
RaiseTheDed@reddit
I've never checked the brakes in the air, but I will probably adopt that. I usually don't use much brakes at all in GA though, I let the airplane slow itself down most of the time
MeatServo1@reddit
We learned WARNBB at the aviate academy: weather, altitude, radio (com), nav (radio), briefing, and brakes.
1E-12@reddit (OP)
Is that like after start engine checklist?
MeatServo1@reddit
Descent flow, backed up by a do-verify checklist. You want to hear the weather so you know whether it's within your aircraft limitations and personal minimums, know the field altitude and the pattern altitude (final approach / glideslope altitude) for planning purposes, what the correct com radio frequency is, what the correct nav radio frequency is if you're flying an approach, the visual or instrument approach briefing, and check the brakes so you can plan what to do if one or both has failed.
1E-12@reddit (OP)
Oh that makes more sense
live_drifter@reddit
Depends on what plane and what brake
_Gizmo_@reddit
Imagine testing your brakes on final and the piston(s) gets stuck without realizing it. I think I'd prefer no brakes than stuck brakes haha
spectrumero@reddit
No, because if both brakes are working consistently, my aircraft will keep going straight while stopping. Doing them independently doesn't gain anything. If only one brake is working, the aircraft will turn as it has a free castoring tailwheel.
It might be worth doing on a nosewheel plane with a solid linkage (e.g. PA28) which will still keep going straight regardless, especially at low speed.
Jwylde2@reddit
Total overkill. If the plane pulls in one direction when stopping, you’ll know something is wrong.
grumpycfi@reddit
And you're sure it's left and right foot not left and right seat?
1E-12@reddit (OP)
Yes and from the comments seems like it's a thing
TheLurkingGrammarian@reddit
Yes, but it's more to check the roll and balance clock is working as expected before a full stop check.
It's good to know roll and balance are reading correctly before you leave the ground.
brightlife28@reddit
Every flight. Both pilots. And then checked again in the air during the landing checklist. It’s a fun little surprise when you start braking and one side doesn’t work at all.
skunimatrix@reddit
And I check the handbrake so 3 brake checks....ha...ha...ha. Why do I get the picture of the count in my head when I said that...
methodeum@reddit
Was SOP at my flight school
1E-12@reddit (OP)
So, when you press on one brake during a brake check does the aircraft turn due to asymmetric braking - or is it too slow to induce a yaw?
Asking because (like anonymous 4071 said) if it does turn then it seems like every brake check would also be testing the L and R "independent" function.
"Did we stop?" "Yes -> at least one brake works" "Did we turn?" "No -> confirmed both brakes are working"
cficole@reddit
I've had the brake on one side fail, on a PA-28. Even going slowly, I had a noticeable yaw when braking. I had to apply the brakes very slightly, and early, to maintain close to a straight line, when stopping.
assinyourpants@reddit
You’re looking for brake fluid leaks. I usually am say something like “your brakes look good?” And he says “yeah” and then we brake test and then move. Should be SOP.
nl_Kapparrian@reddit
Seems unnecessary since a normal brake check already checks both sides, but it doesn't hurt anyone to do additional checks before you get in the air. One thing I like to do is lean then enrich the mixture during to run up while watching for equal rise and fall of EGTs.
Flat-Row7968@reddit
That’s a great idea, new thing added to my checklist 🙂
1E-12@reddit (OP)
Off topic but still interesting. You have a display for each cylinders EGT I guess?
nl_Kapparrian@reddit
Yes. G1000
Legitimate-Watch-670@reddit
On most trainers the brake systems are completely independent of each other, so it's not really possible to not "test them independently".
Students have a tendency to crank too hard when testing left and right individually, puts a lot of side load on the nose wheel. So maintenance asked us to stop after a few flat tires. Just hitting them both smoothly together when you start moving is sufficient. You'd notice pretty easily if they're somehow cross wired lol.
DrRob@reddit
I end up doing the left/right test from always overshooting the taxiway centre line after rounding the corner off the apron...
lnxguy@reddit
Is that to ensure they both work the same? Seems like pulling one way would do that.
galloping_skeptic@reddit
I used to do a hybrid approach. My instructor would add power straight ahead and let us get to (I'm making up numbers here) 2 knots and then apply both brakes at the same time. I would let us get up to 3-4 knots and then apply the left brake about 1 second faster than the right brake. The difference was minimal, but if one brake grabbed and the other did not, you would definitely notice. The amount of yaw that was induced by the difference was small enough to ignore but enough to recognize. The big key was that you let the aircraft come back to a full stop before you let off. If either side failed, you would know before you left the ramp.
redtildead1@reddit
I’m a tap left, tap right, full braking kind of guy. Generally about that point is when I find that once again the right brake is soft as hell and barely works
youre__@reddit
After the right brake broke on my last [attempted] flight, I think I will be adopting this approach. Both at the same time should give the same effect, but one at a time plus both reduces risk of overlooking a warning sign.
1E-12@reddit (OP)
Did your brake failure result in an accident? Sounds like you discovered the problem before takeoff...
youre__@reddit
I made a post about it a few days ago on this sub. Fortunately no accident, just a close call. We almost veered off the taxiway as we were leaving the runup area. Had we not stopped in time, we would have gone off the taxiway and descended down a grassy slope into bushes.
Substantial-End-7698@reddit
I don’t think it’s necessary to teach technique for something as simple as a brake check.
1E-12@reddit (OP)
To each their own.
BeenThereDoneThat65@reddit
If it stops in a straight line you have do be exactly that
Virian@reddit
That’s what the Airplane Flying Handbook says to do.
Philly514@reddit
Yeah of course? If one of your brakes is about to fail and it does on a short field landing you can guess what happens when one brake goes full on and the other isn’t working..you’ll flip the plane.
moringaoil@reddit
Hmmmm
rFlyingTower@reddit
This is a copy of the original post body for posterity:
Just recently heard of someone who checks their left and right brakes independently before taxi (like: Roll -> stop with left brake. Roll -> stop with right brake).
Does anyone else on here do this? It never even occurred to me but it makes sense.
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