When gliders fail in flight, but pilots manage to land

On Sunday, June 24, 2018 at 2:19:22 PM UTC-7, Andreas Maurer wrote:
On Sat, 23 Jun 2018 14:56:05 -0700 (PDT), son_of_flubber
wrote:

Bruno Vassel recalls how the control stick broke off in a glider pilot's hand and how that pilot landed the aircraft safely (using rudder to turn and trim to control speed).
https://www.youtube.com/watch?v=kF0tTzvU8IM&t=411s

Another favorite scenario is 'one spoiler stuck open'... the pilot opened the other spoiler to match and landed promptly.

Spoilers frozen shut... slip to land.

What else breaks and what if anything could be done about it?


1. L'Hotellier links.

Had one serious incident yesterday:
ASW-20, l'Hotellier of the (inner) wing flap unlocked, causing the
wing flap to go slightly negative after two minutes of aerotow.
According to the pilot he had done a full control check after
assembling the 20.
He needed nearly full aileron to keep the glider level and land it
successfully.


The (inexperienced) pilot made the follwing mistakes:

- Didn't lock the l'Hotellier connection properly (obviously)

- Made the approach and landing with flaps 4 (positive). With the
negative inner flap one one wing this resultetd in a serious
asymmetric lift configuration.

- Pilot approached faster than usual (115 kp/h, 60 kts) with flaps 4.
Aerodynamical forces at this speed pushed the unconnected flap even
further into "negative", increasing the asymmetric lift.


The pilot obvously didn't know how his wing flaps worked - setting
them to 2 or 1 (negative) would have solved the asymmetry and only
needed an additional 7 kts higher approach speed.


2. ASW-24
Elevator trim bowden broke while thermalling and trim was set
significantly tail-heavy. Experienced pilot landed safely, but had to
push the stick forward all the time.


Cheers
Andreas

Another check on controls (lacking help) is to back drive them: Move the aileron on one side and watch the stick and aileron on the other side. Move the elevator and observe the stick move. On some gliders you can pull open the spoiler paddle (once unlocked) and see the other one come up. This demonstrates continuity through the fuselage, and is an indicator that things are connected.

Not sure everyone understands how the rudder control system in most of our ships, works. Typically, a cable on each side from the rudder to the pedal with a spring at each pedal (to keep the pedal erect). If a cable breaks or becomes disconnected, the pedal on that side will be pulled forward by its spring........ends up flat on the floor! Meanwhile, the spring on the other rudder pedal will pull in uncommander rudder! Sensing this, the pilot tries to correct with opposite rudder, but that puppy is flat on the floor! Next, the pilot applies opposite aileron before the uncommanded rudder gets out of hand. This works, but the ship is now flying in a full slip!
This is exactly what happened to two pilots flying an ASH-25, a few years back and they were on the ridge! The PIC flew away from the rocks, in a full left slip and made a radio call giving his location, situation and intentions (bail out). Hearing his call, I thought for a few seconds, then asked if the rudder pedals in the other seat were working? Anxious seconds later, a much relieved voice reported that, in fact the front seat rudder pedals were working normally. They headed for the nearest airport with the front seat pilot holding enough right rudder pedal to keep the rudder near neutral.
Something to add to your bag of tricks,
JJ