Instructions for Flying the Grob 109
Some of this information is specific to FFN
Speeds to Fly
Takeoff 55, climb 60
(The book may give speeds a little lower than these)
Differential Braking – 3 types braking
Toe brakes – left and right wheels at end of rudder travel.
Hand brake – both wheels re hand brake handle centre console, car style
Both brakes together – at end of airbrake extension.
Brakes take some getting used to and are very different to Dimona H36.
Airbrakes overcentre lock – brakes *very* effective.
The scissor-type airbrakes have a strong overcentre lock – push all the way forward to lock, and use a fair bit of pressure to unlock. Brace yourself when unlocking, or brakes may come open all the way. Sooner or later you will fail to lock the brakes pre-takeoff and they will pop open – usually at about 50 feet! Practise a surprise airbrake deployment so you’ll know what to expect. Keep speed below about 70 when doing this so as not to overstress them.
DO NOT USE AIRBRAKES FROM RIGHT SEAT
As a general rule, do not attempt to land from right seat. It is known that some pilots get seriously crossed up.
Crosswinds – left crosswind takeoff only
Nominal max crosswind component is 11 knots, but with experience this can be exceeded with left crosswind. Right crosswind is always to be avoided.
Magnetos (FFN specific)
CDI switch is 3 position (but should be a two position switch).
This aircraft has a secondary ignition system. The CDI is activated by a 3 position switch clearly marked CDI/Start. In the CDI position, the starter motor cannot be activated. In the START position the CDI is off. In the centre position both are off – a bit of a trap if you’re on the ridge.
VSI/Vario switch (FFN specific)
Use “Motoring” position for motoring, “Vario” for soaring.
Feathering and Pitch
System is somewhat different to Dimona H36
Feathering handle is the larger of the two, the top one. To feather, cut motor after changing back to fine pitch and cooling (remember to turn off CDI also). Pull handle all the way out and turn to lock.
1500rpm for fine, 2200rpm for coarse.
From fine, drop revs to 2200rpm, give pitch handle a short, firm tug. Pull it out and release it in one smooth movement which takes about a second. Difficult to describe correct technique, best to have a demo from someone who knows the knack.
If it has gone into coarse correctly, when given power the max revs should be only around 26-2700, but if it’s still in fine it will go through 3000.
From coarse, drop revs to 1500rpm, give pitch handle a short, firm pull as described above. Test for fine by applying full power. Often it will not go in the first time.
Get into the habit of always engaging fine pitch during power-on landings, and before shutting down for soaring. It is possible to take off in coarse pitch, but the first time you do it may well be the last.
No Right Seat Command
Unless pilot *really* knows what they’re doing. Far too easy to get left & right confused resulting in loss of control.
Chaotic, followed by Four F’s & Four C’s
F Fuel on
F Fuel supply
F Fuel pump on
C Carbie heat
C Cowl flaps (n/a this aircraft)
Three final checks before rolling: – Canopy – Airbrakes – Fuelpump
Adjusting Prop pitch
Tools: 13mm ring/open, small shifter or approx 8mm openender
Slacken 8mm nut about 4 to 5 mm so that rollpin is free to rotate with 13mm open ender.
Rotate inner ring counter clockwise to coarse. (mark it first)
Rotate only one or two positions (ie about 1 or 2/12ths)
Ensure roll pin is back in position before tightening 8mm nut.