G109 100 Hourly Inspection
Maintenance Manual GROB G 109
(Adapted from photocopy supplied by GFA c1990)
3.4 Inspection and maintenance items
Subject of inspection &/or maintenance
Section 1. Engine (clean)
1. Cowling: check for cracks, dents and loose or missing connectors
2. Fire resistant colour check, correct damaged areas (Wiedoko 4
-Brandschutzfarbe N 56582/weiB)
3. Valve rocker clearance adjust , cold (inlet/exhaust: 0.2 mm /
0.008 in. ) (slightly more with cast iron barrels - 0.010in)
4. If necessary, replace rocker box cover gaskets
5. Remove spark plugs from cold engine, check gap 0.4 mm (0, 016
in. ) and clean with plastic brush.
Recommended spark plug exchange interval: 150-200 hours (Note
2)
6. Compression check ( for further details consult engine manual)
7. Check for leaks at oilpressure and temperature sensors
8. Perform oil change (warm engine /max. 2.5 litres )
9. Clean sump oil screen
10. Fuel lines - check for leaks , safety-wired and wear.
11. Remove fuelfilter cap, clean screen, install and safety-wire.
12. Oil level check of Stromberg-Zenith carburetors
13. Carburator diaphragm check and fill up Zenith lube oil (for
further details consult engine manual )
14. Airfilter check, clean and damp with oil
15. Electrical wiring check for damage, wear and secure attachments.
16. General condition of clamps, fittings and linkages (Throttle,
choke , and carburetor linkages)
17. Engine mounts check for cracks, looseness of mounts, and looseness
of engine to mount.
page 23a
18. Check alternator drive belt tension and condition
19 Time magneto to engine (for further instruction consult engine
manual)
20. Fuel pump: clean screens (both electric and mechanical)
21 Check ignition harness for security of mounting clamps, damage
and tight connections at spark plug and magneto terminal
22. Mounting of starter,alternator and magneto secure and tight.
23. Starter wheel check for damage.
24. Check crankcase for leaks and cracks.
25. Cooling ribs of cylinders clean, no cracks or other damage.
26. Crankcase breather line secure and tight.
27. Lubricate magneto snapper with appx. 10 drops. of oil.
28. General condition of exhaust system, corrosion and burnt-through
areas and remove heat exchanger. Check attaching flanges at exhaust ports
of cylinder for evidence of leakage. If leaks exist, remove exhaust system,
machine flat and re-assemble with new gaskets (Subaru or Beetle 1300) (Note
1)
29. Heat exchanger condition and tightness
30. Fresh and warm air hoses check for leaks and general condition
31. Fresh air duct panels tight and no damage
32. Fire wall grommets and fairleads (sic) condition
Also at 50hrs: Carb diaphragms, time magneto.
Page 23b:
Propeller (see also Owners Manual for variable propeller models HO-V62/HO-62R)
1. Remove spinner and check for dents, cracks and roundness.
2. Check blade installation or absence of blade shake and radial
play (angle) to one degree.
3. Check blades for absence of cracks and damage.
4. Watch smooth operation of pitch change.
5. Pitch adjustment, ball bearings, thrust plate without cracks
, wear, play and dirt. The wear of the plate must be less than 0.2 mm (0.008
in.)
6. Grease the four studs with Calypsol H 442 or equivalent.
7. Check visible hub parts for cracks and corrosion.
8. Slightly grease tracks of ball bearings with Calypsol H442 or
equivalent.
9. Pitch limiters without large friction.
10. Check torque moment of stop nuts at the flange attachment of
the prop by applying torque 4,5 mkp (390 in/lbs. ) without loosening the
parts. (32.5 ft/lbs - rjw)
11. Inspect prop blades for even. (sic) (Note 3)
Page 23c
Section 3. Airframe
1. Surface-check for damage, inspect cracks, painting & markings.
2. Pitot tube, jacking rings, airbrake panels & position light
covers secure.
3. Lubricate springs of airbrake panels
4. Aileron hinges: check for corrosion & operation & slightly
lubricate
5. Drain holes clear.
6. Wing fittings check for corrosion & slightly grease.
7. Quicklock fasteners of airbrake & aileron control assy. Inspect
for proper operation.
Grob AD Hotellier in Tailplane: measure w/micrometer 100 hourly &
grease 50 hourly.
(Note 1) Removal of rust followed by a liberal
application of aluminium grease helps keep the steel flanges in good condition
and makes it easier to keep an eye on the weld between the steel flange
and the stainless steel header pipe. Exhaust pipe gaskets (the round ones
between the header and the muffler) are small diameter type from early
Beetle 1300, not the later 1500 type.
(Note 2) An unauthorised but very simple solution to a common
sparkplug problem is to fit two copper plugwashers instead of the usual
one. This brings the tip of the plug thread fairly level with the face
of the combustion chamber, preventing deposits building up on the protruding
threads and also alleviating problems with the cylinder head temperature
sensor. This trick is also used in the Byron Gliding Club's MotorFalkes.
It works with Champion REL37B plugs, and may work with Bosch WB240ERT1
plugs.
(Note 3) To check evenness of prop blades, place a marker close
to the tip of one blade, then rotate prop 180 degrees. Marker should be
within 5mm or so - the propellor manual should state the limits. Periodic
checking of tacho accuracy is also recommended.
Cooling: In Australian conditions, the standard G109 Limbach
motor tends to run very hot. Fitting a Kombi oilcooler, a NACA duct
to the cooler, and an
extended sump (and running Penrite oil) has solved the problem - the
oil temp remains below the red even in the hottest outback summer conditions,
and generally settles down to about 80 degrees during cruise. It actually
runs a bit cold in winter.
If Penrite or similar quality oil is unavailable, expect a ten degree
rise in temperature and lower oil pressure.
More on cooling modifications
Rudder Removal can be quite tricky. Here's
how to make it simple.
Tailwheel Assembly information
Other info:
Alternator Belt - 10*500 Continental RO-HT-FZ
(numbers printed on Continental belt: FO10/Z 520 LiZ
20 1/2 (half symbol, ie small 1 over small 2)
Alternator: Ducelier 22/30A (some have Bosch alternator)
Alternator Brushes for Ducelier: Bosch brushes may be modified for
the purpose.
Brakes
Carburettors - Stromberg 150 CD-3
Electric Fuel Pump - Hardi model H cat
2212.
Magneto - Slick 4230
Bearings: Tailwheel 6004LLU, Mainwheel 6006RS
Bearings: Propellor pitch actuator fork 626ZZ (some A models take 2
bearings, some 4)
Carpet - Cockpit: Happich 7720033
Crankshaft and conrods: Porsche 914
Starter Motor - Fiat, Bendix type. |
 |
| FFN: Current engine is a Porsche 914 based Limbach, upgraded by Aeropower
of Perth with a heavy duty crankcase and running dual plug heads. Rated
at 80hp @ 3300, but rarely sees more than 3000 in the climb due tipspeed
and cruises 2650/2700 at 80/85 knots.True hp I would guess around 60/65.
Dual CV carbs by Stromberg provide excellent economy - 13 litres per hour.
Fuelburn 1 hp for 1 hr 0.284 litres of fuel per hr.
Therefore 13 litres / hr divided .284= 45.77 HP
|
Propellor Pitch Adjustment
Tools: 13mm ring/open, small shifter or approx 8mm openender, and a
good quality Philips for the spinner screws.
Remove spinner
Slacken 8mm nut about 4 to 5 mm so that rollpin is free to rotate (use
13mm open ender)
Feather prop
Rotate inner ring counter-clockwise to coarsen. (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.
Propellor Pitch Actuator Bearings
Bearings: Propellor pitch actuator fork 626ZZ 6x19x6. (some A
models take 2 bearings, some 4)
Grob109B bearings differ (like almost everything else) and are 6x22x6
Grob 109 Torque figures
Propellor flange nuts torque: 35-37 ft/lb, 48-50nm
Cylinder Head Torque 12/18 ft/lb (check this!)
Brakes
Brake caliper seals for automotive fluid - for Clevland calipers (same
calipers on G109A & Dimona H36)
Part# info on bag:
BS218 X 10
C/D-1Q02
B/N-245057
from Halray Brake Reconditioning
7/5 Krauss Avenue South Lismore
02 6621 4029
Caliper Piston Seals - original Cleveland items are for aviation brake
fluid, but o/ring seals for automotive brake fluid are available. (RJW
has some of these - property syndicate 0807)
Brake Calipers - Cleveland 30-9 (FFN stamped 389)
Bleed nipples on G109 calipers - spanners
sizes: 7/16" & 1/4"
Brake Master Cylinders - Grimeca
Brake discs - cast iron - G109 & H36 probably same
Dimona H36 Brake Fluid - From the manual.
7.3 BRAKE FLUID:
The Brake Fluid used is SAE J 1703 (SAE 70 R3)
or FMVSS 116 DOT 3. The aircraft MIL-5606 is NOT to be used (RED). When
adding fluid, pay attention the fluid does not spill over on painted surfaces.
Insure the cap for the reservoir can vent to the atmosphere. Before adding
Brake Fluid, attempt to determine why fluid is needed.
.............
So, it appears likely that some H36 Dimonas brought to Australia ex-Thai
airforce had been changed over to aviation milspec brake fluid. Something
to beware of.
