Duo Discus XLT Comp #4

Operating notes for P1s.

The following notes are based on experience gained over the last year of operating the Duo Discus XLT. They in no way replace any information that’s contained in the flight manual (copy in the glider). If you are unsure about anything that is stated below, then please come and ask.

The minimum P1 flying requirements for the Duo are 500hrs P1, current cross country pilot, and have flown at least two 300km flights. You will need a briefing and a check flight with an instructor. The office hold a list of the instructors who are cleared to do this.

  • Pre-Flight
  1. Batteries: – The glider has Life Po4 batteries that are specifically for this glider. The two soaring and engine battery should be taken out and kept on charge when not in use. The fin battery is charged from the connecter in the cockpit, and this should be plugged in every evening.
  2. Battery change over switch has four positions

‘F’ battery (tail) recharged in situ via cable in hangar

‘C1/C2’ soaring batteries

‘E’ for engine use only

  1. Fuel to be filled by CFI/DCFI only. 1.30 mix with Avgas
  2. Leave fuel cock ON at all times
  3. Engine extend on manual control. Check compressions, prop hub and blades.
  4. Cockpit loading – use placard in cockpit. For water ballast, use flight manual.      CAUTION – last 2 litres of fin ballast cannot be dumped unless the fin tape is removed.

The glider has the latest engine control unit which is a single switch extend and retraction unit, with the ignition also coupled to this switch. The manual switch should only be used on the ground, or in the air to retract the engine if the auto cycle has failed

 Operating the engine.

  1. Engine priority selector to P1’s seat
  2. Fuel cock open
  • Pitot/static switches down
  1. 50kts
  2. Ignition on - Observe flashing green transit light
  3. Green on - Engine extended
  • Decompress – 55kts - 60kts (Do not exceed 70kts)
  • Engine starts – Nose up – 51kts(Blue line)– Run engine for minimum 30 seconds.

 Failure to start

  1. Try decompress at higher speed.

 Engine Shutdown

  1. 50kts
  2. Ignition off
  • Observe green transit light. Engine will go to ½ cock for stopping the prop.
  1. Listen for 3 ‘clunks’ – solid green light – Engine stowed
  2. Pitot/static switches up.

 Most field landing accidents that involve turbo gliders are the result of the pilots getting the priorities wrong, and spending too much time trying to start the engine. Please follow the order of priorities below.


  1. Always Pick suitable field first.
  2. Start engine above 1000ft AGL
  3. If failure to start – Put the Ignition switch down, and continue field landing. engine extended. Glide angle 1:18 – Attempt smooth landing.

The new Duo has a number of subtle differences  from the other duo on the fleet. The items below are some of the possible traps for the unwary. 

Common operating faults

  1. Airbrakes are powerful - Do not retract rapidly in the flare (flaps retract with lift loss).
  2. The glider has a canopy support strut which should be used whenever the canopy is open. The strut helps protect the front canopy hinge
  3. Ensure canopy is in fully down position prior to locking shut. Check by feeling the locking pins.
  4. Emergency canopy jettison is the normal red operating handle on the left hand side.
  5. Take care with ground handling – Tail is very heavy.

The glider has all weather covers that should be fitted on the glider when not in use. Because of its size there is no allocated parking place for the Duo in the main hangar. Along with the Falke it should be kept at the front of the hangar, and taken out each day. Because it has all weather covers it can be left outside during the day.

Colin Watt.

CFI Lasham Gliding Society                                                                           

Feb 2018