My glider came with L'Hotellier fittings on both the airbrake and aileron connections.

In 1997 the Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 97-08-06 to address an issue of unaltered L’Hotellier fittings which can become uncoupled during flight. This can obviously result in the loss of control of the aircraft. What would typically occurred is that the L’Hotellier capture/release mechanism was not fully engaged during assembly and/or worked loose during flight.

There were three possible solutions to prevent inadvertant disengagement from happening:

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Method: Drill a hole in the L’Hotellier fitting’s release mechanism to allow the insertion of safety wire, safety pin or a safety clip. This is the default minimum solution.

• Pros
  1. Simply mechanical solution.
  2. "Permanent" fix.
  3. Works on both straight and right angle L'Hotellier fittings.
• Cons
  1. Requires modification of the L'Hotellier fitting.
  2. Difficult to fit the safety wire in place during assembly (in my glider these connections must be made by feel).

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Method: Use of a knurled nylon Uerling sleeve. This rotates over the L'Hotellier ball joint.

• Pros
  1. Simplest to install.
  2. Simplest to operate.
  3. No modification of the l'hotellier fitting required.
  4. Only solution which directly prevents the separation of the l'hotellier ball from the socket. The other solutions prevent the l'hotellier release mechanism from being inadvertantly activated (or not being latched in the first place).
• Cons
  1. Non-permanent fix. I have been told that sleeves must be replaced every 2 years.
  2. Difficult to find. Unfortunately, I have been unable to locate replacement Uerling sleeves. (2010 update - I have been told that Pacific Aerosport sells them)
  3. Uerling sleeves only work on straight L'Hotellier connections (i.e. airbrakes in DG-100/101, 200/201) but not on right angle connections (i.e. ailerons in DG-100/101, 200/201).

MOST SECURE CHOICE

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Method: Use of a Wedekind-Sicherung (“LS Safety”) sleeve which captures the L'Hotellier release mechanism.

• Pros
  1. Very simple solution to operate.
  2. "Permanent" fix. Once installed, no further maintenance.
  3. Works on both straight and right angle L'Hotellier fittings.
• Cons
  1. Costliest of the choices.
  2. Most complicated to install.

Good luck. Do a positive control check before each flight. Fly safely.

• A very good description of the different solutions with images shown here.
• Jim Phoenix's pictures and instructions of Wedekind installation on a Nimbus 4 from his web site are shown here.
• Nick Juergen's Wedekind instructions are available here.
• Here is some more documentation that I have gathered.

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