Introduction - 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 which 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 then worked loose during flight. My old glider came with L'Hotellier fittings on both the airbrake and aileron connections (but not the elevator assembly).
The makes and models of gliders impacted by this AD are;
- Alexander Schleicher: ASK21, ASK23, ASW12, ASW15, ASW15B, ASW17, ASW19, ASW19B, AS12 and AS-K13,
- Centrair: S.N 101, 101A, 101P, 101AP, and 201B
- Eiriavion: PIK 20, PIK 20B, and PIK 20D
- Glaser Dirks: DG100, DG400, and DG-500M
- Burkhart: Grob G102 Astir CS, G102, G103 Twin Astir, G103 Twin II, G103A Twin II Acro, G103C Twin III SL, G109, and G109B
- Intreprinderea: ICA (Lark) IS-28B2 and IS-29D2
- Rolladen Schneider: LS1-f and LS3-a
- Schempp-Hirth: Cirrus, Std. Cirrus, Nimbus 2, Nimbus 2B, Janus, Discus a, Ventus a/16.6
List of L'Hotellier Fitting Fixes
There were four (4) possible solutions to prevent the inadvertent disengagement of the L'Hotellier fittings from happening. These are listed below.
NOTE: Not all solutions shown below will work with every glider listed above. Each model of glider may require a fix for the ailerons, or airbrakes, or flaps, or elevator, or a combination thereof. Consult your glider's manuals for identification and location of all L'Hotellier fittings.
Drill a Hole & Insert a Pin/Wire
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
- Simply mechanical solution.
- "Permanent" fix.
- Works on both straight and right angle L'Hotellier fittings.
- Cons
- Easy to loose inside the glider unless attached by a thin lanyard.
- Difficult to fit the safety device in place during assembly (in my glider these connections must be made by feel).
- Requires modifying the L'Hotellier fitting.
Drill a Hole & Insert a Schempp-Hirth Spring
Method: Drill a hole into both the release mechanism and the body of the mechanism cup. Purchase or fabricate a captive wire "spring" that is semi-permanently installed on the L'Hotellier ball joint. One end of the spring rotates into the hole in the L'Hotellier ball joint engagement push lever.
- Pros
- Simple to install.
- Simple to operate.
- Cons
- Requires modifying the L'Hotellier fitting.
- Can be somewhat expensive.
Uerling Sleeves of LS Safety Sleeves
Method: Use of a (often knurled) nylon Uerling sleeve. This rotates the sleeve over the L'Hotellier ball joint and physically prevents a premature release.
- Pros
- Simplest to install.
- Simplest to operate.
- No modification of the l'hotellier fitting required.
- 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
- Non-permanent fix. I have been told that sleeves must be replaced every 2 years. NOTE: To extend the life of Uerling sleeves install them by sliding onto the end of the L'Hotellier connector - do not snap them over the top as this can deform the sleeve.
- Difficult to find. Unfortunately, I have been unable to locate replacement Uerling sleeves. (2010 update - I have been told that Pacific Aerosport sells them)
- 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).
Wedekind Sleeves
Method: Use of a Wedekind-Sicherung spring-loaded sleeve which captures the L'Hotellier release mechanism.
- Pros
- Very simple solution to operate.
- "Permanent" fix. Once installed, no further maintenance.
- Works on both straight and right angle L'Hotellier fittings.
- Cons
- Costliest of the choices.
- Most complicated to install.
- Sources
L'Hotellier Fitting Maintenance - Here is a document that explains maintenance and inspection of L'Hotellier fittings.
My glider initially came with safety pins. Soon afterwards I upgraded to Uerling sleeves. Finally, I installed Wedekind sleeves which ended up being the very best option.
Please see this document for all information I have on how to secure L'Hotellier fittings and which also details my installation of Wedekind-Sicherung sleeves on a DG-101G ELAN with many images of the complete installation process along with sources for the parts.
Good luck. Do a positive control check before each flight. Fly safely.
Miscellaneous Information
- A very good description of the different solutions with images is 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 other L'Hotellier fitting documentation that I have gathered.
