Purpose

The purpose of this OAN is to alert pilots of potential undercarriage collapses in DG-300 and DG-303 gliders linked to pilot operation errors.

How does this affect you?

In the last year there have been five undercarriage collapses in DG-300/DG-303 gliders. There have been engineering fixes released for the gliders. There is also potential for pilot undercarriage control manipulation causing issues.

How to manage this risk

DG Aviation GMBH released TN359/22 in June 2004 “To facilitate the locking of the landing gear in extended position a torsion spring which rotates the handle into the lock will be installed instead of the friction disc.” Maintenance Approved Persons should check to see if this TN is applicable and fitted to the aircraft.

DG Aviation GMBH released Service Information 01-1991 in January 1991. This Service Info describes the installation of a resin block.

When the landing gear control is moved to the down and locked position, the pilot should try and pull the control into the up position without unlocking the handle. When down and locked there will be no space between the control lever handle and the fuselage wall when in the locked position. The control will not move towards the pilot.

It is possible to push the lever handle forward to near the down and locked position, where the handle is not hard against the cockpit wall. When pushed sideways to the cockpit wall, it will spring back! This is an important visual and tactile cue that the undercarriage is not locked down. Pulling the handle back will not be impeded by the locking mechanism.

Small pilots must ensure their backrest / parachute / cushion is adjusted so that they can reach the full forward travel of the undercarriage lever. This needs to be stressed in conversion briefings.

Opening the airbrakes when the undercarriage is down and locked is not a reliable guide as the warning system maybe mal-adjusted or not functioning.

A video is available which shows the problem: