C152 rudder lock?

[FlyingGoat]

A club Cessna is permanently parked outside in all weather. The owner is keen for us to use a home-made rudder lock (2 strips of wood, held firm with nut and bolt), particularly with forecast strong wind conditions, overnight (wing tie-downs as well).

Fair enough, though I don't know if this is common practice elsewhere.

What are your opinions on this procedure, keeping in mind the obvious potential accident risk for anyone whose pre-flight checks are a bit hit-and-miss?

[mad_jock]

Some one will eventually forget it.

I wouldn't have thought you needed to bother with a cessna because the rudder is connected to the nose wheel.

You need them when the rudder can swing about but not if the nose wheel is on the ground

[cattardbezzina]

I wouldn't have thought you needed to bother with a cessna because the rudder is connected to the nose wheel.

You need them when the rudder can swing about but not if the nose wheel is on the ground

Don't agree with that. The rudder is attached directly to the rudder pedals by control cables, BUT the rudder pedals are attached by springs to the nose wheel, allowing the rudder to move in place on the ground, even when the nosewheel is firmly on the ground as well. There is nothing that locks the rudder in place while the aircraft is parked on the ground and it just flops around in the wind making it very susceptible to damage.

The owner is keen for us to use a home-made rudder lock (2 strips of wood, held firm with nut and bolt

All the Cessnas I rent from my local club are fitted with this type of rudder lock while parked. Unfortunately, its somewhat bad design from Cessna's part and they don't even supply a rudder lock as far as I know - thats why they are all 'home made'.

Some one will eventually forget it.

Not if you follow your checklist prior to takeoff - which should hopefully include a full control surface movement check!

Happy landings.
Claude

[mad_jock]

Folk have taken off with concrete tie down blocks attached.

It will happen

The springs are more than stiff enough to stop the rudder moving. And to be honest it being blown over to the side helps unload the tail and allows the air to spill around the fin making it less likely that the plane will wx cock.

[mad_jock]

I could see that happening as well.

And as I have personally never seen a rudder damaged in in the wild winds of scotland where nobody uses rudder locks to my knowledge

The additional risk of someone not taking them out means its not worth it. If the plane required it you would get one with the aircraft or it would have a built in pinning point like most aircraft have that the rudder can flap about.

[Pilot DAR]

The springs are more than stiff enough to stop the rudder moving

If this is the case, that aircraft is non conforming, and requires maintenance before flight.

In short, definately install a rudder lock on any single engine Cessna which will sit out in the wind. EVERY night my 150 sits outside, I will install a rudder lock.

It' a shame that Cessna did not provide more provision for this until the Caravan, which has an ideal design for this.

In more detail, most Cessna nosewheels steer when commanded on the ground, but they do not steer in flight (PA 28's do, and are quite different). The Cessna nosewheel has a centering cam (which you can easily see) which locks the nosewheel forward once it extends all the way.

Obviously, the rudder still works in flight, as it is directly connected to the pedals. The nosewheel is connected to the pedals via two compression springs (which are inside those two white steering pushrods which go to the nosewheel). So, in flight, when you push a pedal, the rudder moves, but the nosewheel does not move, the affected spring compresses.

Therefore, on the ground, if the nosewheel is stopped from turning by friction of the tire to the ground, the rudder will still move (and tke the pedals with it) if blown on the ground. You can move it during your walkaround - the nose wheel does not move when you do. It you look at the two nosewheel steering pushrods while your buddy moves the rudder, you'll see them compress.

So, no, those two springs will have no affect to prevent rudder damage in a wind.

To take this to the next step of seriousness, the 150/152 are the subject of an AD, with respect to rudder control stop failure/lock. The affect is said to be the rudder going to the stop when commanded so in flight, then staying there despite all efforts. This has caused several fatal accidents. A major causal factor in these failures is the rudder bellcrank being damaged or loosened in the rudder structure, very likely from being repeatedly banged against the stops in the wind.

So, Please use the rudder control lock on a Cessna, if it provided to you, and please remove it before flight. If you forget to remove it, you'll find steering to taxi very difficult, and probably figure out your error in a few feet of taxiing :E

[Pilot DAR]

If the plane required it you would get one with the aircraft or it would have a built in pinning point like most aircraft have that the rudder can flap about.

Well Cessna does not give you one (they don't give you a ladder to reach to fuel either) but they do instruct the use of one:

"Section 5

Care of The Airplane

.....

MOORING YOUR AIRPLANE

.....
(2) Install a control lock over the fin and rudder
....."

From 1972 Cessna 206 POH, just as a sample...

[smarthawke]

To expand a little on Pilot DAR's excellent description of the C152 rudder control system, there are also two springs (in tension) attached to the rudder bars onto the aircraft structure. These keep the rudder straight - when they break (and they do) the rudder will be 'floppy' when moved by hand on the pre-flight and won't return to centre by itself.

I designed a simple wooden wedge when I looked after a fleet of C152s which fits either side in the gap between the fuselage mounted rudder stop and the rudder horn (where the cable attaches).

This keeps any forces on the rudder acting through the strongest part of the structure and doesn't damage the paintwork. I had the two wedges joined with a piece of string and a warning flag hanging off that.

Darwinian Award seekers could take off with the locks in place as long as they don't attempt to move the non-moving rudder pedals and steer on the ground with the brakes.

Because it is a closed non-sprung circuit from the rudder pedals back to the rudder (direct cables), the rudder pedals and rudder do not move. There's a clue there for the dim that something isn't right.

Such people probably won't take the control lock out or remove the pitot cover. You can only protect people against themselves so far. Far better to protect your aircraft and not let people like that anywhere near it...

[Big Pistons Forever]

When I owned a C 150 I made a rudder lock that was 2 pieces of orange painted light plywood about 6 inches wide and long enough to span from the leading edge of the vertical fin to the trailing edge of the rudder. They were lined with carpet and had a bolt at each end. The wide surface spread the load and it was pretty obvious so it would be hard to miss on the walk around.

As for whether or not it is needed, well all I can say is the Cessna parked beside mine had the rudder damaged in a wind storm. The repair was almost 3000 dollars :{

I find the argument that using a rudder lock could result in someone forgetting it unpersuasive. A prominent well marked external lock is hard to miss. Anyone who does is going to show plenty of earlier signs as to his/her unfitness to use your airplane before they do something that stupid and should already be weeded out.

[FlyingGoat]

Many thanks for the feedback - much appreciated.

Maybe the eccentricities of the 152's parking brake needs a thread of its own?

[Genghis the Engineer]

Maybe the eccentricities of the 152's parking brake needs a thread of its own?

What parking brake? I always thought that was just an extra knob to play with when you get bored, as it seems to have roughly zero braking effect.

G

[thing]

I think the clue's in the name.....it's not meant to be a braking system, just a parking brake. I know this because I asked exactly the same thing about our Cessnas and got exactly the same answer.

[high wing harry]

The school I learnt at used to have 8 C152s. In forecast strong winds when the little spam cans couldn't be squeezed into a hangar somewhere they did have a similar home built rudder lock as you describe.

However the then-Chief Engineer was not a huge fan because the rudder when free to move will also allow the aircraft to align itself into wind very quickly and effectively which will limit damage anyway.

May I suggest a homemade lock might also have some pretty ribbons attached to aid the pilot who can't do a walkround properly and notice these things!

Mind you, I too have witnessed a pilot drive their aircraft onto the runway still attached to two large concrete tie-downs!! Shame because the runway had just been re-tarmaced and still shows the signs of the scraping...

[Maoraigh1]

However the then-Chief Engineer was not a huge fan because the rudder when free to move will also allow the aircraft to align itself into wind very quickly and effectively which will limit damage anyway.

While securely tied down?:(

[Big Pistons Forever]

Maybe the eccentricities of the 152's parking brake needs a thread of its own?

You mean the pilot "No Touch" knob:=

The parking brake system on all the small Cessna's consists of a couple of wire cables which pulls on the brake master cylinders. It is a crappy system because it will not usually apply equal brake pressure to each wheel so the airplane can swivel around the wheel with lesser pressure. Also it has a nasty habit of not fully relaxing when the parking brake is selected off which causes the brakes to still be slightly engaged which will quickly trash the pads and in extreme cases cause the disks to warp from overheating.

I teach all my students to never use the parking brake. They are instead to chock the aircraft whenever they are not in it.

Pipers on the other hand have an excellent effective pretty much fool proof system.

[Pilot DAR]

I teach all my students to never use the parking brake. They are instead to chock the aircraft whenever they are not in it.

Yes, exactly!

[Genghis the Engineer]

Most types I practice, and teach - stop, put the parking brake on, shut down, chock / tie-down, then release the parking brake.

Before flight - parking brake on, chocks / tie-downs out, start up, parking brake on - pre-taxi checks, parking brake off.

Difference is on most C15* aircraft I've ever flown, the parking brake is inadequate to keep the aeroplane in one place even with the engine at idle on startup.

G

[BackPacker]

The parking brake system on all the small Cessna's consists of a couple of wire cables which pulls on the brake master cylinders.

I knew from the few flights I've done in Cessna's that the system was crappy. But this crappy?

In all those years, why did nobody come up with a retrofit alternate system like the PA28 (an extra hand-operated cylinder that applies brake pressure) or the DR400 (a valve which locks in the brake pressure after applying it through the rudder pedals).

I mean, the brake system in essence is already hydraulic. How hard can it be to insert an extra valve in the system, or a T and an extra hand-operated cylinder?

[Pilot DAR]

On the other hand, how often have you heard of a C 15x landing with the parking brake applied, or landing with no braking available because of misuse of the system? Or, landing with lots of braking, taxiing in, and applying the parking brake, which can weld the pads into place on the discs? Or leaving the brakes set, as someone tows the plane away. These are all easily accomplished in other types. The parking brake system of the 15x is undeniably simple, but if well maintained, and operated as intended, works adeqautely.

Mine works well every time I use it. I use it once a year, to be sure it works as required, at annual inspection time.

I am very nervous when right seat (often to a more experienced pilot), and see the parking brake applied, and then the engine(s) started, with little attention paid to the possibility of motion on the ground. It that case, I will then hold the brakes myself, until the other pilot takes control. If I am read the prestart checklist item "Parking Brakes Applied" I read back "Brakes applied" as I hold them.

Properly serviced aircraft brakes give you lots of stopping/holding ability for only a moderate investment in muscle. If I am in control of an aircraft with the engine(s) running, and I don't want it to move, I will be applying pedal pressure, having it chocked, or shutting it down. Your application of pedal pressure is your mental cue that you are in control of an aircraft under power, and you are resonsible for it.

If you feel that you lack the personal strength or endurance to hold the aircraft on the brakes for as long as you might have to, either consider improving your fitness, or arrange for a ramp assistant to provide and remove chocks.

If you have a long hold on a taxiway, aircraft should be pointed into the wind anyway, and most aircraft will hold at idle with only gentle brake application.

[BackPacker]

So what you're essentially saying is that the crappy design is actually a feature. Because you will not use the system at the wrong time, or for the wrong reasons.

Well, I can't argue with that...:E

But I agree that a parking brake should be used for "parking" only. That means you only rely on it when the engine is stopped. And still, preferably, chock the aircraft anyway.

Anytime the engine is running, you apply the brakes yourself directly, not through the use of the parking brake. Particularly during the runup.:ok:

[VP-F__]

If your aircraft does have to live outside then the best option is to keep it pointing into wind anyway, obviously not that practical if you live a decent drive away. With a 172, same rudder arrangement to the 150, they will weather cock happily into wind if allowed to. The clever arrangent with the control lock keeps full nose down and the shape of the wing means virtually no lift is generated. If in doubt look at a 172 pointed into 60+ kts and the tie down lines will be slack! As for the rudder the homemade control lock is the way forward, I can think of various checklist items which if not completed satisfactorily will lead to a short and unhappy flight so should not be used as an excuse for putting a rudder lock on. In my experience anything over about 20 knots will start having the rudder moving, having it banging against the stops is simply stupid. As for a different aircraft type, the BN Islander, the rudder is cable linked, not spring loaded, to the pedals and nose wheel and if that is not rudder locked it can still reach the stops in a strong enough breeze, a whack on the stops and a crease in the rudder there is very pricey.....

[smarthawke]

A minor point of note, the control lock on a C152 keeps the elevators only about 10 degrees (aircraft) nose down whereas the C172 lock keeps the elevators fully down.

One to watch when pushing a 172 backwards on uneven ground - the inboard elevator tips will hit the ground before anything else...

I can't grasp the theory when the rudder is not locked that the aircraft weathercocks as surely the rudder will deflect 'down wind' and therefore reduce the amount of 'wind alignment' that would be offered by a locked rudder where the rudder and fin would be acted on by the wind. (That was far too long a sentence...).