Hypothetical Scenario #1 - Urgent Action required

This is a voluntary pop quiz.

You're circling in a 30 degree left bank at 3000 AGL.

You hear a thunk and the glider enters a spin. Your practiced spin recovery technique does not work in the usual amount of time. You look in the direction of the thunk and see that the left spoiler is full open, you confirm that the spoiler control handle is in the fully closed position. A quick look confirms that the right spoiler is full closed.

What do you do next? Why did the left spoiler pop open. What just happened?

To derive the full benefit of this exercise, you might respond to this thread with your answer before looking at any of the other replies.

My hypothetical solution and explanation follows as the next comment.

First of all if it is a spoiler as on early Schweizer gliders it would be blown to the closed position.

If the drag devices you speak of are actually air brakes, as they are likely named in the POH, you have a problem.

This confusion can be deadly.

Robert Mudd
CFIA-G

On Wednesday, February 5, 2014 9:19:04 PM UTC-7, OneTango wrote:
You look in the direction of the thunk and see that the left spoiler is full open, you confirm that the spoiler control handle is in the fully closed position. A quick look confirms that the right spoiler is full closed.



What do you do next? Why did the left spoiler pop open. What just happened?



To derive the full benefit of this exercise, you might respond to this thread with your answer before looking at any of the other replies.



My hypothetical solution and explanation follows as the next comment.

This is my best guess. I have no idea if it is correct.

What do you do next?

Use the spoiler handle to open the right spoiler to match the left.

Follow my practiced spin recovery technique and return to level flight with both spoilers fully open.

Decide whether to land or bail out.

If there is a place that I can land with both spoilers fully open. Do that..

If I cannot make it to a field with both spoilers open, quickly determine if it is possible (and if there is less sink) to fly with one spoiler open and one spoiler closed. If it is possible, decide whether to try it or bail out.

Why did the left spoiler pop open?

When the push rod that controls the spoilers locks past the detente, it is under compression and it is designed to bend slightly. Due to a manufacturing defect, the bent aluminum push rod rubs against the fiberglass where it passes through a wing rib (hole is not in exactly the right place or hole is not the right shape or size). Over time, the glass wing rib saws through the aluminum pushrod. At a certain point the pushrod buckles and breaks. The spoiler pops open.

On Wednesday, February 5, 2014 8:42:13 PM UTC-8, OneTango wrote:
This is my best guess. I have no idea if it is correct.



What do you do next?



Use the spoiler handle to open the right spoiler to match the left.



Follow my practiced spin recovery technique and return to level flight with both spoilers fully open.



Decide whether to land or bail out.



If there is a place that I can land with both spoilers fully open. Do that.



If I cannot make it to a field with both spoilers open, quickly determine if it is possible (and if there is less sink) to fly with one spoiler open and one spoiler closed. If it is possible, decide whether to try it or bail out.



Why did the left spoiler pop open?



When the push rod that controls the spoilers locks past the detente, it is under compression and it is designed to bend slightly. Due to a manufacturing defect, the bent aluminum push rod rubs against the fiberglass where it passes through a wing rib (hole is not in exactly the right place or hole is not the right shape or size). Over time, the glass wing rib saws through the aluminum pushrod. At a certain point the pushrod buckles and breaks.. The spoiler pops open.

Your scenario #1 actually did happen in a DG-400 at Truckee about 25 years ago. One spoiler needed to be adjusted slightly, so the (non mechanic) pilot gave the quick disconnect fitting a half turn in. Under positive G force the fitting was now trying to pull away from the ball, rather than being forced into to ball. At about 4000 feet AGL, one spoiler popped full open. The pilot correctly assessed the situation and pulled the other spoiler open. Having plenty of altitude, he decided to enter the pattern to the normal glider runway (19) at 2000 feet..........thinking that extra altitude is always good, right? The extra altitude meant he had to fly farter down-wind to get rid of his excess altitude, turned final into some wind and didn't make it back to the runway! Landing short of 19 at Truckee means you hit a cliff.

If you are faced with this situation (one spoiler open), Put the ship in the middle of the longest runway available!
JJ

On Wednesday, February 5, 2014 11:19:04 PM UTC-5, OneTango wrote:
This is a voluntary pop quiz. You're circling in a 30 degree left bank at 3000 AGL. You hear a thunk and the glider enters a spin. Your practiced spin recovery technique does not work in the usual amount of time. You look in the direction of the thunk and see that the left spoiler is full open, you confirm that the spoiler control handle is in the fully closed position. A quick look confirms that the right spoiler is full closed. What do you do next? Why did the left spoiler pop open. What just happened? To derive the full benefit of this exercise, you might respond to this thread with your answer before looking at any of the other replies. My hypothetical solution and explanation follows as the next comment.

Dive brake became uncontrollable. It does not matter why.
Apply opposite rudder and unload the wing by neutralizing the stick in pitch while also neutralizing aileron. Open other dive brake to balance assymetrical drag that is helping add yaw in the spin.
Upon recovery, determine if the glider is controllable with one brake open. It will be in any case I would expect.
Get to landable place with one brake out(less drag than 2).
Fly a bit tighter pattern to allow for what is effectively 1/2 brake.
Go to full brakes from high final to balance and allow "normal" landing.
UH

I'd say you open the righthand spoiler as well, recover from the spin
(if needed) and start looking for a nice place to land you glider...

Okko (netherlands)



Op 6-2-2014 5:19, schreef OneTango:
This is a voluntary pop quiz.

You're circling in a 30 degree left bank at 3000 AGL.

You hear a thunk and the glider enters a spin. Your practiced spin recovery technique does not work in the usual amount of time. You look in the direction of the thunk and see that the left spoiler is full open, you confirm that the spoiler control handle is in the fully closed position. A quick look confirms that the right spoiler is full closed.

What do you do next? Why did the left spoiler pop open. What just happened?

To derive the full benefit of this exercise, you might respond to this thread with your answer before looking at any of the other replies.

My hypothetical solution and explanation follows as the next comment.

I've been thinking this would be a fun scenario to practice on a BFR, to give the student (who will surely appreciate it) practice at handling an emergency that really isn't an emergency.

When the student checks airbrakes on his/her downwind checklist (what downwind checklist? Ah, on the second flight then!), I grab the airbrakes and say "the airbrakes just stuck open." And shut up. Now the student's job is to quickly plan a full airbrake plus slip pattern. It's not a real emergency, because we can always close the airbrakes.

Has anyone tried this? UH, font of all wisdom on such things?

John Cochrane

On 2/5/2014 9:19 PM, OneTango wrote:
This is a voluntary pop quiz.

You're circling in a 30 degree left bank at 3000 AGL.

You hear a thunk and the glider enters a spin. Your practiced spin
recovery technique does not work in the usual amount of time. You look in
the direction of the thunk and see that the left spoiler is full open, you
confirm that the spoiler control handle is in the fully closed position. A
quick look confirms that the right spoiler is full closed.

What do you do next? Why did the left spoiler pop open. What just
happened?

As others have said: 1) unstall the wing (reduce angle of attack/stick
forward); 2) recover from the spin/rotation (SOP per ship); 3) verify
condition; 4) (if necessary) implement "situation plan" A (or B or C,
depending on actual circumstances).

After landing - do spend a few moments congratulating yourself for being
prepared and for handling the situation correctly/safely.

This is the sort of "mental scenario playing" that can be time well spent,
indeed. Winter need not be all bad!!!

Bob W.

I agree with Otto.

The linkage has broken somewhere, sounds like between over-
centre lock (behind bulkhead) and between R and L spoiler
actuation rods.

Chris N
At 14:24 06 February 2014, okko kloosterman wrote:
I'd say you open the righthand spoiler as well, recover from the
spin
(if needed) and start looking for a nice place to land you glider...

Okko (netherlands)

Try pulling the spoiler handle to get symmectrical controls. Of course,
you'll now be landing quite soon so look for a landing spot. If no good
options are available, bail out.

I'd guess a connection in the spoiler circuit for one wing failed.

"OneTango" wrote in message
...
This is a voluntary pop quiz.

You're circling in a 30 degree left bank at 3000 AGL.

You hear a thunk and the glider enters a spin. Your practiced spin recovery
technique does not work in the usual amount of time. You look in the
direction of the thunk and see that the left spoiler is full open, you
confirm that the spoiler control handle is in the fully closed position. A
quick look confirms that the right spoiler is full closed.

What do you do next? Why did the left spoiler pop open. What just
happened?

To derive the full benefit of this exercise, you might respond to this
thread with your answer before looking at any of the other replies.

My hypothetical solution and explanation follows as the next comment.