Hypothetical Scenario #1 - Urgent Action required

Are your examininees required to so no-spoiler approaches all the way to landing in glass (K-31/G-103)?

The PTS no longer require no spoilers all the way to landing. An examiner should not be asking for it.

To go all the way to landing, it helps to stay in the slip during roundout. Fine for the pilot, very nerve wracking for instructor, as if the student decides to put it on the ground going sideways you don't have time to react..

I've found the slip to landing very educational for a totally different reason, and explaining this to students helps to "sell" an otherwise unpopular and stressful maneuver. Yes, you are very unlikely to face a spoiler failure -- and if you do, going to land somewhere a lot longer than the airport might be a better option.

The no spoiler pattern is great training to avoid all of beginner's usual mistakes, especially in high stress situations like their first off field landings. The key is to make the pattern big, and with super precise airpseed control -- not too close and too fast, like most early off field landings.

It takes a few seconds to establish slip, and it seems to take a few seconds for slip to really bite and produce a good sink rate. Hence a long final leg is key.

A big misconception is that you do it by flying a super low pattern. Actually a well established slip produces a very nice sink rate and you don't have to be low.

So selling it as "we're going to do a pattern at normal height, but nice and wide and super precise airspeed, to prepare you for off field landings" helps generate some enthusiasm,

John Cochrane

On Thursday, February 6, 2014 9:16:48 PM UTC-6, wrote:

The PTS no longer require no spoilers all the way to landing. An examiner should not be asking for it.

We are having a bit of an issue with that...

To go all the way to landing, it helps to stay in the slip during roundout. Fine for the pilot, very nerve wracking for instructor, as if the student decides to put it on the ground going sideways you don't have time to react.

Nerve wracking for the next guy waiting to fly the plane, too!

I've found the slip to landing very educational for a totally different reason, and explaining this to students helps to "sell" an otherwise unpopular and stressful maneuver. Yes, you are very unlikely to face a spoiler failure -- and if you do, going to land somewhere a lot longer than the airport might be a better option.

We actually had a G-102 spoiler handle break off inflight, resulting landing on field was long and ended up in fields past end of runway. No real other damage or injury, but could have been worse. So it can happen.

The no spoiler pattern is great training to avoid all of beginner's usual mistakes, especially in high stress situations like their first off field landings. The key is to make the pattern big, and with super precise airpseed control -- not too close and too fast, like most early off field landings.

Ok, how do you have super precise airspeed control in a fully developed slip? Last time I tried it in glass (K-21, and my LS6) the airspeed was precisely zero!

It takes a few seconds to establish slip, and it seems to take a few seconds for slip to really bite and produce a good sink rate. Hence a long final leg is key.

Agreed, a high long final lets you really get into that slip and drive it down to the threshold, then gives time to slow down (while still in the slip). Skill is to practice varying the speed (i.e. nose position/AOA) in the slip to control rate of sink, and be able to accurately slow down as you get close to ground, while still in slip.


A big misconception is that you do it by flying a super low pattern. Actually a well established slip produces a very nice sink rate and you don't have to be low.

Bingo! We are scared of students (who may not like the slip) trying to avoid it by making the pattern flat. Bad habit, that!

So selling it as "we're going to do a pattern at normal height, but nice and wide and super precise airspeed, to prepare you for off field landings" helps generate some enthusiasm,

Excellent point. My idea is to break it down into two parts (if using a slippery glass ship). First, using an comfortable touchdown aimpoint, fly a slipping pattern down to the preflare, then straighten out and land normally with spoilers - this to practice the slip without worrying about the landing. Next, fly a normal pattern to the threshold, but in the flare, close the spoilers and demonstrate the result of too much airspeed in ground effect and actually try to land without spoilers before running out of runway.


Kirk
66

Opening the functioning airbrake makes the ship symmetrical again. You've
done an "airbrake stuck open" pattern, haven't you?


wrote in message
...
All very good answers. I thought someone might mention direction of turns
by now. With the one airbrake open it may be very hard to raise that wing
again in a turn if it is the low side wing. Wouldn't it be wise to fly the
pattern with the spoiled wing on the high side of the turns? ie - if your
right airbrake is open you would want to do a left hand pattern? I would
hate to get to pattern altitude and discover I can't raise my wing with the
broken airbrake out after making the first turn...

Bruno -B4

Open the (right) spoiler and try spin recovery.
Maybe left spoiler actuating rod got loose.

At 04:19 06 February 2014, 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
recover=
y technique does not work in the usual amount of time. You
look in the
dir=
ection 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
l=
ook confirms that the right spoiler is full closed. =20

What do you do next? Why did the left spoiler pop open.
What just
happene=
d?

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

My hypothetical solution and explanation follows as the next
comment.

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.

Deploy the other spoiler/airbrake. It is unlikely that the ailerons/rudder
will have the authority to counteract the rolling/yawing moment produced by
a single deployment. Normal spin recovery to approach attitude/speed. With
both spoilers deployed you are still flying a glider, I concede that it is
a glider with a crap gliding angle but if you have ever flown a primary you
will be right at home. You can fly a normal circuit (pattern) with the
normal rules for a glide angle that you now have. It may be wise to ensure
that you do not go any further downwind than the boundary of your selected
landing area, depending on length available, but again the normal rules
apply.

On Saturday, February 8, 2014 6:02:56 AM UTC-5, Don Johnstone wrote:
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.



Deploy the other spoiler/airbrake. It is unlikely that the ailerons/rudder

will have the authority to counteract the rolling/yawing moment produced by

a single deployment. Normal spin recovery to approach attitude/speed. With

both spoilers deployed you are still flying a glider, I concede that it is

a glider with a crap gliding angle but if you have ever flown a primary you

will be right at home. You can fly a normal circuit (pattern) with the

normal rules for a glide angle that you now have. It may be wise to ensure

that you do not go any further downwind than the boundary of your selected

landing area, depending on length available, but again the normal rules

apply.

Heck I've flown Hang Gliders for 38 years so you simply fly it as a trainer -

Similar failure happened on a Nimbus 4DM some years ago - on a fast
final glide into Gariep.

Height was low, speed was high (well past Vmo) when they hit a powerful
thermal.
Wings took the shock, but one airbrake actuator failed under the shock
load. It had been damaged by "buzzing" over an extended period - the
caps were not held down properlyso the blade would chatter in it's box
on pull ups. This set up fatigue in the connecting rod which snapped
under the sudden whip motion on the wing.

Due to high speed, no spin departure.
The resulting yaw caused an immediate roll toward the open brake wing.
Pilot correctly assessed the situation, opened the other airbrake and
attempted to recover from the inadvertent barrel roll.
Attempt was unsuccessful, wings failed symmetrically at the outer panel
join, and then a couple of metres from the root - conveniently
preserving the failed actuator and the witness marks... Calculated
failure somewhere on the far side of 300km/h and enormous g.

Fuselage impact was a couple of seconds later - both pilots being
ejected many metres from the point of impact.
Being a DM the resulting fire destroyed much of the confetti that
remained. Somehow, enough of one of the three loggers remained for a
trace to be obtained.

Moral of that story is - check your airbrake actuators for wear and
fatigue - particularly on long flexible wings. And have some respect for
the numbers - they are there for a reason.

Time from initial failure to impact was maybe 30s. Think about how fast
you can close the distance to the ground next time you are at 250km/h
and 600 feet height.
That height is the distance you are travelling in three seconds (70m/s).

Bruce


On 2014/02/06 4:02 PM, JJ Sinclair wrote:
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


--
Bruce Greeff
T59D #1771

On Saturday, February 8, 2014 12:35:58 PM UTC-8, BruceGreeff wrote:
Similar failure happened on a Nimbus 4DM some years ago - on a fast

final glide into Gariep.



Height was low, speed was high (well past Vmo) when they hit a powerful

thermal.

Wings took the shock, but one airbrake actuator failed under the shock

load. It had been damaged by "buzzing" over an extended period - the

caps were not held down properlyso the blade would chatter in it's box

on pull ups. This set up fatigue in the connecting rod which snapped

under the sudden whip motion on the wing.



Due to high speed, no spin departure.

The resulting yaw caused an immediate roll toward the open brake wing.

Pilot correctly assessed the situation, opened the other airbrake and

attempted to recover from the inadvertent barrel roll.

Attempt was unsuccessful, wings failed symmetrically at the outer panel

join, and then a couple of metres from the root - conveniently

preserving the failed actuator and the witness marks... Calculated

failure somewhere on the far side of 300km/h and enormous g.



Fuselage impact was a couple of seconds later - both pilots being

ejected many metres from the point of impact.

Being a DM the resulting fire destroyed much of the confetti that

remained. Somehow, enough of one of the three loggers remained for a

trace to be obtained.



Moral of that story is - check your airbrake actuators for wear and

fatigue - particularly on long flexible wings. And have some respect for

the numbers - they are there for a reason.

Very interesting report, we had a Nimbus 4DM come apart at Minden and both pilots were killed several years back. They got into a death spiral for unknown reasons..............wonder if one spoiler could have popped open to start the spiral? The accident report stated that both spoilers deployed when the ship was near vertical, but now I'm wondering if one was open before the other? I have seen instances where one spoiler came out caused by bending of its pushrod or flexing of drive unit in the root rib, but nothing broke! Would the accident investigator notice a bent rod or flexed root rib in a pile of fiberglass rubble?
JJ

In one of the early replies, One Tango mentioned the bending of the pushrod and rubbing on the fibreglass "rib." I have seen this but rather than a rib, it was the opening into the spoiler boxes on an SZD Junior. The thin fibreglass of the opening was rubbing on the pushrod and sawing through it like a hacksaw. It was happening primarily on one wing with the other side just starting to leave a mark. We discovered it because there was a problem with this aircraft where one spoiler would open at a slightly before the other so we tried adjusting it to get them to open and close at the same time as well as open to the same height. We started this process because the spoilers did not seem to want to stay locked and as we tested it noticed they were not actuating at the same time. Adjustment required removal of the pushrods and that was when we found it. A review of the logbooks showed that the aircraft had an accident early in its life and one wing was replaced with a brand new one. As the investigation continued, we also found that the pushrod actuating gears were "crunchy" on the original wing but smooth on the other new wing and when we pulled it out of the wing (not an easy task but can be done through an opening in the root rib) we could find no damage but they did not feel right. These gears do not have bearings so the initial thought was not the problem. I was able to discover online that there was a fatality when a Junior spun in after one spoiler opened. The conclusion was that the teeth on the nylon-like gears had sheared off. It may be that the tolerances were such that they did not mesh properly or it was a material fault. We decided to order a new gear set along with the a replacement pushrod. However, none of this explained the differing operation of the spoilers that was the cause of our initial investigation. In the end, we figured out that when the wing was replaced, the fittings had been improperly installed in the torque tube in the fuselage. Accuracy is very important. When a wing is replaced, the collars that are installed on the torque tube do not come predrilled. You have to fit the wing, mark the place where the holes are to be drilled from inside the fuselage and then take it apart and install the collars (anyone who has assembled a Polish glider knows what these are.) Anyway, we finally solved the problem after installing new collars on both sides, a new pushrod and a new gear set.

So, a real lesson here. An accident, an inaccurately installed new wing fitting, the wrong pressure on the pushrods to try to get them adjusted so they would lock (just barely), the resulting rubbing on the spoiler boxes that was swing the pushrods. Aircraft was flown like that for 10 plus years. Finally a new aircraft mechanic said he would not sign it off because it didn't feel right (but he didn't know what the problem was.) A lot of hours spent three aircraft mechanics and myself to discover and then resolve each of the issues described above. Now the aircraft is finally correct. Had the new aircraft mechanic not exercised a high degree of caution to start the process in the first place, it was only a matter of time (maybe many years, maybe soon) where the pushrod on the new wing or the gear set on the old wing would have failed, that is if an accident wasn't first caused by the spoilers popping open.

As an aside, it appears that two things happened around the same time: the fatality when the gear set failed and a change in the company that manufactured the Junior. Whatever the cause, the newer gear sets appear to be made of a different material than the old ones. The old ones were a white plastic and the new ones are black. I would suggest anyone with a Junior look to see what they have, keep an eye on it and inspect the lateral rear sides of the pushrods where they enter the spoiler box. It is tricky to do because if you pull the spoiler up to peek in, the pushrod is pulled deeper into the wing but with a small mirror or an inspection camera it likely can be done. The alternative is to remove the pushrod which is a pain because it is really hard to remove and replace the attachment inside the wing blind at the root end.

Stuck open airbrakes? Why yes we have!
On the Grob, a good strong arm can hold against the student trying to close the spoiler. Once he realizes he can't close the spoilers and declares the problem and turns toward the airport, the emergency is resolved. Spoiler control is given back to effect a safe final touch down.
BillT