Rotax 912 Series Maintenance Manual
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Rotax 912 Series Maintenance Manual

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m.c. gragard
March 17, 2025

can not get 912m to idle below 2000rpm.how to fix?

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1 comments:
Mr. Anderson
March 17, 2025

To fix a Rotax 912 Series engine that will not idle below 2000 RPM, follow these steps:

1. Adjust Idle Speed: Use the idle speed adjustment screw to lower the idle RPM. Ensure that both screws are turned the same amount.
2. Check Engine Smoothness: If the engine does not run smoothly, adjust the mixture screw as needed.
3. Perform Pneumatic Synchronization: Use vacuum gauges to ensure both carburetors have an equal flow rate at idle.
4. Verify Mechanical Synchronization: Ensure the carburetors are properly synchronized before adjusting idle speed.
5. Check for Air Leaks: Inspect the intake system for leaks that could cause high idle.
6. Inspect Throttle Cables: Ensure throttle cables are properly adjusted and not holding the throttle open.
7. Secure the Aircraft: Before making adjustments, ensure the aircraft is properly secured.

If the problem persists, further inspection or consultation with an authorized ROTAX technician may be necessary.

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Summary of Contents for Rotax 912 Series

  • Page 2: Table Of Contents

    11.10) Treatment of corrosion and surface damages ..........32 11.11) Engine preservation and engine back to operation .......... 32 11.11.1) Preservation of a new engine ..............33 11.11.2) Engine back to operation ................33 Periodic maintenance ..................34 Effectivity: 912 Series page 2 Initial issue, Jan. 01/2002...
  • Page 3 Resistance values of the ignition unit ............64 13.4.8) Wiring diagrams ..................65 13.4.8.1) Wiring diagram for ignition system("Single Plug") ...... 65 13.4.8.2) Wiring diagram for ignition system ("Central plug") ....66 Effectivity: 912 Series page 3 Initial issue, Jan. 01/2002...
  • Page 4 14.4.11) Propeller shaft disassembly ................ 96 14.4.12) Gearbox components check ................ 97 14.4.13) Propeller gearbox refitting ................99 14.4.14) Disk spring pre-tension adjust ..............100 14.4.15) Propeller gearbox installation ..............101 Effectivity: 912 Series page 4 Initial issue, Jan. 01/2002...
  • Page 5 15.2) Wear limits for ROTAX® 912 S/ULS .............. 122 Form Sheets ....................123 16.1) Form Sheet for Cylinders and Pistons for ROTAX® 912 UL/A/F/ULS/S ..123 16.2) Form sheet for ext. generator ................. 124 16.3) Form sheet for crack inspection ..............125...

  • Page 6: Index

    Drive for hydraulic governor 93 Propeller gearbox installation Push rods 113 Intake manifold 118 Propeller gearbox refitting 99 Interference suppression box Propeller shaft 32 Propeller shaft disassembly 96 Introduction 13 Push rods 113 Effectivity: 912 Series page 6 Initial issue, Jan. 01/2002...
  • Page 7 Surface damages 32 symbols 13 Table of amendments 10 Technical documentation 13 Temperature measuring system Temperature sensor 77 Tightening torques 31 Trigger coil set 72 Trigger set 62 Trouble shooting 61 Effectivity: 912 Series page 7 Initial issue, Jan. 01/2002...

  • Page 8: List Of The Current

    2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 Effectivity: 912 Series page 8 Initial issue, Jan. 01/2002...
  • Page 9 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 2002 01 01 Effectivity: 912 Series page 9 Initial issue, Jan. 01/2002...

  • Page 10: Table Of Amendments

    003 04955 date of remark for date of approval date of chapter page change approval from authorities inclusion signature english version ÷16 1 up to 125 02 01 01 not required Effectivity: 912 Series page 10 Initial issue, Jan. 01/2002...
  • Page 11 AIRCRAFT ENGINES MAINTENANCE MANUAL II fig. 003 04955 date of remark for date of approval date of chapter page change approval from authorities inclusion signature Effectivity: 912 Series page 11 Initial issue, Jan. 01/2002...
  • Page 12 AIRCRAFT ENGINES MAINTENANCE MANUAL II Effectivity: 912 Series page 12 Initial issue, Jan. 01/2002...

  • Page 13: Introduction

    9) Auxiliary equipment For further information see relevant Operator’s Manual of the engine type 912. 10) Description of design For further information see relevant Operator’s Manual of the engine type 912. Effectivity: 912 Series page 13 Initial issue, Jan. 01/2002...
  • Page 14 AIRCRAFT ENGINES MAINTENANCE MANUAL II Effectivity: 912 Series page 14 Initial issue, Jan. 01/2002...

  • Page 15: Maintenance

    11) Maintenance 11.1) General note See Maintenance Manual type 912 (Line Maintenance) Chapter 05-00-00 para 2.1. In this chapter the maintenance of engine Type ROTAX 912 is described. The ® Manual is subdivided into sections that contain the description and function of the...

  • Page 16: Auxiliary Tools

    (copper bar). fig. 018 00141 Effectivity: 912 Series page 16 Initial issue, Jan. 01/2002...

  • Page 17: Measuring Tools

    Resistance range 200 Ω ÷ 2 MΩ Accoustic continuity tester. ® Oscilloscope:TEKTRONIX 2225 or equivalent (optional) 2 channels Analogous Sensitivity 5 mV to 5V/div Frequency limit 50 MHz WARNING: Using these instruments, observe the manufacturer’s specifica- tions. Effectivity: 912 Series page 17 Initial issue, Jan. 01/2002...

  • Page 18: Special Tools And Devices

    ..............1 for magneto flywheel 841 875 hex. screw M16x120 DIN 931 ..........1 for extractor 877 360 insertion sleeve ..............1 for oil seal 32x52x7, crankshaft, magneto side Effectivity: 912 Series page 18 Initial issue, Jan. 01/2002...
  • Page 19 877 315 measuring plate ..............1 to check plain bearing protrusion 38 ÷ 39 877 230 trestle ass’y ................1 for chucking the engine 876 762 trestle support ass'y ............. 1 Effectivity: 912 Series page 19 Initial issue, Jan. 01/2002...
  • Page 20 25x52x15, oil seal 30x52x7 60 ÷ 63 876 489 puller cap ass’y ..............1 for ball bearing 15x32x8 and needle bearing 22x28x12 941 730 hex. screw M6x80 DIN 933 ..........1 Effectivity: 912 Series page 20 Initial issue, Jan. 01/2002...
  • Page 21 877 377 extractor ass'y ............... 1 877 570 Tapping drill M18x1 .............. 1 To clean the thread at exhange of coolant bend 877 245 trestle support ass'y ............. 1 Effectivity: 912 Series page 21 Initial issue, Jan. 01/2002...
  • Page 22 877 800 0.01mm 4 5 6 S W 4 6 S W 4 1 8 7 7 8 7 7 4 5 0 4 4 0 877 260 fig. 019/1 04926 Effectivity: 912 Series page 22 Initial issue, Jan. 01/2002...
  • Page 23 REPAIR TOOLS FOR GEARBOX 8 7 6 8 8 5 8 7 6 4 8 9 7 6 0 0 8 7 7 60 5 8 7 7 5 9 0 fig. 019/2 03083 Effectivity: 912 Series page 23 Initial issue, Jan. 01/2002...

  • Page 24: Consumable Materials

    G-N, Lubricant ..........100 g 897 870 K&N ® Filter oil 99 - 1131, Bag .......... 15,8 ml 996 943 gasket set, for complete engine ..........1 996 947 gasket set, for complete carburetor ..........Effectivity: 912 Series page 24 Initial issue, Jan. 01/2002...
  • Page 25 ENGINE K&N CARBURETOR gasket set gasket set Filter öl a s w d e r G- n p Effectivity: 912 Series page 25 Initial issue, Jan. 01/2002...

  • Page 26: Motor Oil

    After assembly it cures under hermetical conditions with metal contact. Its surface sealing properties are guaranteed for temperature range between - 55°C and + 200°C (- 67°F to + 390°F). Effectivity: 912 Series page 26 Initial issue, Jan. 01/2002...

  • Page 27: 8) Loctite® "380 Black

    The granulates used are of sizes 40 to 60 µ. The surface roughness to be achieved is 0,5 - 1 µ representing a microfinish of the parts. Effectivity: 912 Series page 27 Initial issue, Jan. 01/2002...

  • Page 28: 14) Lapping Fleece Sr 4600 A - Very Fine Grading

    MOLYKOTE ® GN is applied to both components mated.To application is pointed in case. ® 11.7.19) K&N Filteroil 99 - 1131 To optimize filtration and to protect against moisture. Effectivity: 912 Series page 28 Initial issue, Jan. 01/2002...

  • Page 29: Securing Elements

    Twist wire around the Stretch wires and Turn twisted wire end Cut off excess Bend wire end and screw twist approx. 4 times around screw length of wire press it towards screw fig. 022 Effectivity: 912 Series page 29 Initial issue, Jan. 01/2002...

  • Page 30: 2) Nut Securing

    When using a self-locking nut, take care that the polyamide insert ring on nuts according to DIN 985 as well as the securing element on nuts according to DIN 980 is positioned towards outside. 00146 fig. 023 Various typical applications of safety wiring Effectivity: 912 Series page 30 Initial issue, Jan. 01/2002...

  • Page 31: Tightening Torques

    ..... oil pump ......first hand tight to stop and after trial run retighten by hand banjo bolt ....oil line, pressure side ..M 10x1 ..20 Nm ( 177 in lb) Effectivity: 912 Series page 31 Initial issue, Jan. 01/2002...

  • Page 32: Treatment Of Corrosion And Surface Damages

    Check contact between plugs and/or fasten connections by separation test, if necessary apply contact spray to increase conductivity. 11.11) Engine preservation and engine back to operation Due to the special material of the cylinder wall, the ROTAX aircraft engine needs no ®...

  • Page 33: 1) Preservation Of A New Engine

    912 Series: ROTAX as the manufacturer of the engine warrants for perfect corrosion ® protection of aircraft engine 912 Series for min. 12 months from date of delivery by ROTAX ® This warranty consent is subject to the following conditions: —...

  • Page 34: Periodic Maintenance

    AIRCRAFT ENGINES MAINTENANCE MANUAL II 12) Periodic maintenance For further information see relevant Maintenance Manual type 912 (Line Maintenance) . Effectivity: 912 Series page 34 Initial issue, Jan. 01/2002...

  • Page 35: Maintenance Of The Systems

    The carburetor flange assemblies W can be taken off after removal of the hex. hd. screws M8x20 I and washers O. 04956 ±0,25 7 mm ±0,01 (0,276 in 02611 fig. 11 fig. 10 Effectivity: 912 Series page 35 Initial issue, Jan. 01/2002...

  • Page 36: Bing Constant Depression Carburetor: Check And Maintenance

    With this check the float needle seat is checked for tightness. If the depression is not maintained, pay particular attention during disassembly to the float needle with Viton tip and the carburetor housing. fig. 038 00326 00026 x 0,1 fig. 037 Effectivity: 912 Series page 36 Initial issue, Jan. 01/2002...

  • Page 37: 2) Diaphragm

    NOTE: The jet needle fitted must move freely. Visually check outside of plunger I and the two inside compensa- tion bores. fig. 040 Effectivity: 912 Series page 37 Initial issue, Jan. 01/2002...

  • Page 38: 4) Jets

    T inserted in the float. Check the pins Y for float 00360 support U for wear due to excessive vibration. At noticeable wear replace both floats and if necessary also the float suspen- sion I. 00361 fig. 044 Effectivity: 912 Series page 38 Initial issue, Jan. 01/2002...

  • Page 39: 6) Float Suspension

    Fit float chamber and fix it with spring clip. NOTE: Various float needle valves,see IPC. Higher springrate for the engine type 912 ULS/S schlecht which have a black colored spring pin E. good fig. 046 04928 Effectivity: 912 Series page 39 Initial issue, Jan. 01/2002...

  • Page 40: 8) Starting Carburetor (Choke)

    Reassembly of the carburetor with new O-rings and gaskets in reversed sequence. Apply the 4 countersunk screws M4x14 with Loctite 221. 00363 00362 the fig. shows the fig. 047 fig. 048 carburetor for cyl. 2/4 Effectivity: 912 Series page 40 Initial issue, Jan. 01/2002...

  • Page 41: Check Of The Fuel System

    Do not smoke, no naked flame or sparks. Do not fill tank brimful, allow for expansion of fuel. Never refuel while engine is running. Effectivity: 912 Series page 41 Initial issue, Jan. 01/2002...

  • Page 42: 2) Fuel Pressure

    If during the test run the nominal fuel pressure values are not met, stop engine and start with the trouble shooting procedure. WARNING: Do not start the aircraft before an obvious fault has been found and eliminated! 00365 fig. 050 Effectivity: 912 Series page 42 Initial issue, Jan. 01/2002...
  • Page 43 — The float needle valve cannot retain the fuel pressure over a longer period or during transport of the aircraft. — If problems with fuel supply are encountered and cannot be resolved, contact a ROTAX authorized Distributor or Service Center. ® Effectivity: 912 Series page 43 Initial issue, Jan. 01/2002...

  • Page 44: Carburetor Flange

    (.275 in.). At replacement of the carburetor socket take care of the following: — As on engine of type 912 Series and type 914 Series the old carburetor sockets won't be longer available, a new socket will be used. — On the affected engines old carburetor sockets of the carburetor 1/3 and 2/4 can be replaced separetly and therefor a mixed arrengement is feasible.

  • Page 45: Fuel Pump

    The fuel pump cannot be dismantled. Check for contamination is only possible by endoscope on suction side T. At overhaul the fuel pump must be renewed. The carburetor flange Y is marked with a continuous 6-digit number. 00367 fig. 053 Effectivity: 912 Series page 45 Initial issue, Jan. 01/2002...

  • Page 46: 6) Fuel Tubes

    — see also para 13.1.2. Check connections on fuel pump and on carburetors. Check fuel manifold and check for leaks. Renew damaged fuel tubes. Route the tubes to avoid scuffing during operation. 00368 04962 fig. 054 Effectivity: 912 Series page 46 Initial issue, Jan. 01/2002...

  • Page 47: 7) Carburetor Flange, Carburetor

    40 mm (1,69 in) has to be maintained between cheese head screw U and support bracket Y. ÷ 5÷6 mm (0,2 0,24 in) 40 mm (1,6 in) 04956 ±0,25 7 mm ±0,01 (0,276 in 04958 fig. 220 fig. 221 Effectivity: 912 Series page 47 Initial issue, Jan. 01/2002...

  • Page 48: Lubricating System

    04705 On version 912 configuration 2 and 912 configuration 4 this connection is closed with a plug screw. e = oil pressure sensor. fig. 061 00371 fig. 060 Effectivity: 912 Series page 48 Initial issue, Jan. 01/2002...

  • Page 49: 3) Oil Pump Reassembly

    Spring { 39,5 mm (1,55 in.) long, renew at wear. NOTE: Loctite 221 Loctite 221 Loctite 221 Loctite 221 Loctite 221 Loctite 221 04701 fig. 062 Effectivity: 912 Series page 49 Initial issue, Jan. 01/2002...

  • Page 50: Magnetic Plug

    Tightening torque of banjo bolt u is 17 Nm (150 in.lb). 13.2.4) Magnetic plug Refer to Maintenance Manual 912 Series (Line Maintenance) chapter12- 00-00, para 5.4. 13.2.5) Drain screw See fig. 063.

  • Page 51: Cooling System

    On some engine installations this requires removal or partial lifting of engine. To remove the hex. screw E M16x1,5 from the flywheel hub the crankshaft has to be looked, see Maintenance Manual 912 Series (Line Maintenance) Chapter 12-00-00 para 2.7. 00344 13.3.2)

  • Page 52: Magneto Hub

    Otherwise remove the cable clamps and remove the stator. Cover the groove for Woodruff key with a pro- tective tape to avoid damage to the oil seal. See fig. 070. 00380 fig. 071 Effectivity: 912 Series page 52 Initial issue, Jan. 01/2002...
  • Page 53 Check dimension of bore } (dimension E) of bearing bush for crankshaft support q,(dimension R) , see para 15. 00382 dimensions new mm(in.) wear limit mm(in.) See Dimension Sheets in para 15. 00084 Maß dim. fig. 074 Effectivity: 912 Series page 53 Initial issue, Jan. 01/2002...
  • Page 54 Check rotary seal r for water pump sealing. At emergency of liquid, renew rotary seal and oil seal t. See para 13.3.7. Visually inspect location bore for electric starter. u = Drive shaft for mechanical rev. counter. 00383 fig. 075 Effectivity: 912 Series page 54 Initial issue, Jan. 01/2002...

  • Page 55: 5) Water Pump Shaft Disassembly

    Remove old oil seal and rotary seal utilizing 2 pins Q (approx. 5 mm dia. = 0,2 in.) and suitable punch W. Oil seal and rotary seal will be destroyed at removal and must be renewed. 00386 fig. 078 Effectivity: 912 Series page 55 Initial issue, Jan. 01/2002...

  • Page 56: Rotary Seal Reassembly

    The spring of the rotary seal presses the water pump shaft outwards towards the sealing face Y, depending on axial clearance O. See fig. 079 fig. 082. 00389 00388 fig. 080 fig. 081 Effectivity: 912 Series page 56 Initial issue, Jan. 01/2002...

  • Page 57: 8) Crosssection Of Water Pump

    877 295. Torque to 15 Nm (133 in.lb). Check impeller R for out-of-round. At noticeable out-of- NOTE: round replace impeller or if necessary also the pump shaft. 02873 Maß dim. fig.082 Effectivity: 912 Series page 57 Initial issue, Jan. 01/2002...

  • Page 58: Ignition Housing Reassembly

    The Allen screw O M6x30 reaches into the oil compart- NOTE: ment and must be sealed with LOCTITE ® 221. P = drive shaft for mechanical rev. counter. 00390 fig. 083 04974 fig. 084 Effectivity: 912 Series page 58 Initial issue, Jan. 01/2002...

  • Page 59: 10) Water Pump Housing Reassembly

    180° if required. Fit coolant hoses and fix them with genuine hose clamps. CAUTION: Do not tighten hose clamps, excessively in order not to damage the hose! 00392 fig. 085 Effectivity: 912 Series page 59 Initial issue, Jan. 01/2002...

  • Page 60: 11) Hose Clamps

    Visually check for damages, cracks, chafing marks, burnt spots etc. At noticeable damages replace the air baffle. Effectivity: 912 Series page 60 Initial issue, Jan. 01/2002...

  • Page 61: Ignition System

    — Check all cables and their plug connections for damage and correct connection as per Wiring Diagram (see para 13.4.8). — Check all plug- and screwed connections for oxidation and tight fit. 00397 fig. 091 Effectivity: 912 Series page 61 Initial issue, Jan. 01/2002...

  • Page 62: Electronic Module, Trigger Set

    In both cases the disassembly work described below is necessary (see para 13.4.9 and 13.4.10). NOTE: The electronic modules are marked on the front side with part no. and serial number! 00399 fig. 093 fig.092 00398 Effectivity: 912 Series page 62 Initial issue, Jan. 01/2002...

  • Page 63: Charging Coil

    Assure the iron core Q is not loose. If required, renew the double ignition coil. In this case the disassembly work as described below is necessary, see para 13.4.9 and 13.4.10. 04959 fig. 095 Effectivity: 912 Series page 63 Initial issue, Jan. 01/2002...

  • Page 64: Generator Coil

    11.5. Especially if the failure occurs only occasionally this is necessary. In this case send the complete ignition unit to an authorized overhaul facility, see Maintenance Manual 912 Series (Line Maintenance ) Chapter 05-00-00 para 2.2.

  • Page 65: Wiring Diagrams

    A: 1 and 2 TOP 3 and 4 BOT ignition circuit B: 1 and 2 BOT 3 and 4 TOP NOTE: Fig. 100 shows the wiring dia- gram with 1-pol and 4-pol con- fig.100 nector. Effectivity: 912 Series page 65 Initial issue, Jan. 01/2002...

  • Page 66: 2) Wiring Diagram For Ignition System ("Central Plug")

    0,75 bl 0,75 sw 0,75 or 0,75 sw 0,75 br 0,75 sw 0,5 ws/ge 0,5 bl/ge NOTE: Fig. 100 shows the wiring dia- gram with 1-pol,4-pol and 6- fig.100/1 pol connector. Effectivity: 912 Series page 66 Initial issue, Jan. 01/2002...

  • Page 67: 9) Ignition Electric Set Disassembly

    I with O-rings, compensating tube O, fuel line and ignition electric set can be removed, proceeding with great care. Plug all 4 intake apertures to avoid entry of foreign matter. 00334 fig. 102 Effectivity: 912 Series page 67 Initial issue, Jan. 01/2002...

  • Page 68: 10) Ignition Electric Set Disassembly

    [ can be replaced individually. The ignition cables are screwed in and therefore are renewable. Except for the double ignition coil [ for spark plug 3 top NOTE: and 4 bottom, all are fitted in the same position, with boss ] upwards. Effectivity: 912 Series page 68 Initial issue, Jan. 01/2002...
  • Page 69 AIRCRAFT ENGINES MAINTENANCE MANUAL II 04960 /grease fig. 103 Effectivity: 912 Series page 69 Initial issue, Jan. 01/2002...

  • Page 70: 11) Ignition Electric Set Reassembly

    } with hex. nut M6 and lock washer. = unten / bottom = oben / top ws = weiß / white sw = schwarz / black 00407 Magnetseite / magneto side Propellerseite / propeller side fig. 104 Effectivity: 912 Series page 70 Initial issue, Jan. 01/2002...

  • Page 71: 12) Ignition Electric Set Installation

    13.4.11. Fasten ignition cables for cylinder 1 - 3 and 2 - 4 with new cable strap on coolant hose, see para 13.4.9. 00408 fig.105 Effectivity: 912 Series page 71 Initial issue, Jan. 01/2002...

  • Page 72: 13) Removal Of Trigger Coil Set

    T, these of ignition circuit B are fitted in the lower position. CAUTION: Fit the clamps as to ensure perfect ground connection between shielding and ignition housing. Maß / dim. 00409 fig. 106 Effectivity: 912 Series page 72 Initial issue, Jan. 01/2002...

  • Page 73: 14) Stator Removal And Re-Fitting

    Every stator fixation is screwed together with a loading coil ground line. At assembly apply Lithium grease to the contact faces i of the stator and the screw heads. 00410 fig. 107 Effectivity: 912 Series page 73 Initial issue, Jan. 01/2002...

  • Page 74: 15) Magneto Hub

    The complete set of ignition coils can be withdrawn now. If need be, remove electronic boxes as well, after disconnecting shorting lines from capacitors. Check capacitors, renew as required. Check all other components. Effectivity: 912 Series page 74 Initial issue, Jan. 01/2002...

  • Page 75: 2) Wiring Diagram For Interference Suppression Box

    T primary cable for ignition coil, ignition circuit B, cyl. 3/4, black (ground) ignition circuit A, cyl. 1/2, black (ground) ignition circuit B, cyl. 3/4, white ignition circuit A, cyl. 1/2, white Effectivity: 912 Series page 75 Initial issue, Jan. 01/2002...

  • Page 76: 3) Re-Assembly Of Interference Suppression Box

    Clean contact surfaces as required and use footned spring washer at connection. See Service Instruction SI-25-1994. NOTE: Since design year 1992 the resistance spar- ing plug 12mm DCPR7E was introduced, see SB-912-01. Effectivity: 912 Series page 76 Initial issue, Jan. 01/2002...

  • Page 77: Temperature- And Pressure Measuring System

    — monitoring instrument — cable connection — sensor cable See Maintenance Manual type 912 Series (Line Maintenance) Chapter 05-50-00 para 2.7.If using 100 % anti-freeze (without adding water), coolant residues in the area of the sensor may result in too high material temperature readings.

  • Page 78: Oil Temperature Sensor

    If max. temperature 140°C (284° F) is exceeded, check — oil system — temperature sensor — monitoring instrument — cable connection — sensor cable See Maintenance Manual type 912 Series (Line Maintenance) Chapter 05-50-00 para 2.8. The sensor is grounded directly via the oil pump housing. 04715 CAUTION:...
  • Page 79 — monitoring instrument — cable connection — sensor cable See Maintenance Manual type 912 Series (Line Maintenance) Chapter 05-50-00 para 2.9. The grounding connection of the sensor is directly via the oil pump housing. The sensor resistance values are shown in the resistance/pressure curve beside.

  • Page 80: Maintenance Of Components

    E from starter housing and remove carbon brush holder R together with springs from armature T. Withdraw armature and thrust washer Y from starter housing, clean parts carefully, see para 11.7.15. fig. 114 00231 Effectivity: 912 Series page 80 Initial issue, Jan. 01/2002...

  • Page 81: 2) Electric Starter Single Parts Check

    Check isolating sleeves t of the plus-pole carbon brush y, fig. 116 renew as required. O-rings -rings u and oil seal i at overhaul of electric starter. Renew all Effectivity: 912 Series page 81 Initial issue, Jan. 01/2002...

  • Page 82: Electric Starter Reassembly

    After removal of magneto hub and ignition housing, see para 13.3.3 and 13.3.4, the sprag clutch can be removed. Withdraw idle gear shaft Q and idle gear W and both thrust washers 12,5x21,5x1 E from both sides of the idle gear. Effectivity: 912 Series page 82 Initial issue, Jan. 01/2002...

  • Page 83: 1) Sprag Clutch Removal

    Y, the timing gear placed behind, the pump gear I pressed onto the camshaft and the timing gear O underneath can be removed only after splitting the crankcase. Drive of mechanical rev. counter via worm gear U pressed into camshaft. 00236 fig. 119 Effectivity: 912 Series page 83 Initial issue, Jan. 01/2002...

  • Page 84: 2) Sprag Clutch Disassembly

    { in sprag unit. Fit circlip W in the groove Q with the bevel edge showing to the sprag clutch. im Eingriff / frei drehbar / engaged freely turning fig. 121 5 11 00238 fig. 122 00239 Effectivity: 912 Series page 84 Initial issue, Jan. 01/2002...

  • Page 85: 4) Reduction Gear For Electric Starter

    Place thrust washer E 12,5x21,5x1 onto crankcase. Place intermediate gear Q lubricate intermediate gear shaft R. Fit thrust washer T 12,5x21,5x1 on top of it. 00240 fig. 123 14.2.5) Ignition housing fitting See para 13.3.9. Effectivity: 912 Series page 85 Initial issue, Jan. 01/2002...

  • Page 86: Rev. Counter Drive

    M8 threads T of gear cover. Now the com- fig. 127 plete gearbox can be pulled off with the impact puller Y without damaging the ball 00244 bearing and the propeller shaft. Effectivity: 912 Series page 86 Initial issue, Jan. 01/2002...
  • Page 87 T and on dog gear. The gears are paired as a set and must not be exchanged individually! fig. 128 fig.129 00246 00245 fig. 130 00247 Effectivity: 912 Series page 87 Initial issue, Jan. 01/2002...

  • Page 88: Roller Bearing Removal For Configuration 1 And 2 Only

    Remove extractor ass’y from crankcase. At this procedure the oil seal P is damaged and must be CAUTION: renewed. 00248 fig. 131 Effectivity: 912 Series page 88 Initial issue, Jan. 01/2002...

  • Page 89: Roller Bearing Removal For Configuration 3 Only

    Q. At the opposite side fit nut O together with washer I. By turning hex. screw clockwise, the roller bearing is pressed off together with the oil inlet flange. Remove O-ring fig. 133 Effectivity: 912 Series page 89 Initial issue, Jan. 01/2002...

  • Page 90: Vacuum Pump Disassembly

    Clean fig. 135 00252 bearing seat and check. At this procedure the needle sleeve E, oil seal O and NOTE: ball bearing W are damaged and must be renewed. Effectivity: 912 Series page 90 Initial issue, Jan. 01/2002...

  • Page 91: 6) Drive For Vacuum Pump And Hydraulic Governor Reassembly

    Do not use Teflon tape, sealing paint or thread grease at 00255 fig. 138 connections. Tighten connections exclusively by ring- or socket spanner and ensure correct positioning. Re-torque by 1,5 turns at the most. Effectivity: 912 Series page 91 Initial issue, Jan. 01/2002...

  • Page 92: Hydraulic Governor Disassembly

    O. Care for clean con- necting surface for oil pres- fig. 140 sure hose. If service work is necessary on the propeller governor, it must be sent to the engine manufacturer. Effectivity: 912 Series page 92 Initial issue, Jan. 01/2002...

  • Page 93: 9) Drive For Hydraulic Governor Reassembly

    Install oil pressure line y free of stress on governor flange and on oil pump housing and with hose clamp on fuel pump. The banjo screws tighten to 17 Nm (150 in.lb). 00258 fig. 141 Effectivity: 912 Series page 93 Initial issue, Jan. 01/2002...

  • Page 94: 10) Propeller Gearbox Disassembly

    876 885, until ring halves E come free and can be removed. CAUTION: Depress the dog gear only so far that free movement of this gear is still warranted, as any further depression might destroy the gear cover. Effectivity: 912 Series page 94 Initial issue, Jan. 01/2002...
  • Page 95 30° to 15°. In the course of standardizing of the gearbox the backlash was changed again to 30°, and the gear width, crankshaft and gearbox housing was modified. Refer to: standardization of gearbox for ROTAX 912/ ® 914, SL 912-002.

  • Page 96: 11) Propeller Shaft Disassembly

    NOTE: Commencing with model 1995 onwards size of oil seal w was changed from 40x52x7 into 40x55x7 and hex. hd. 00264 screws } from M6 to M7. fig. 148 Effectivity: 912 Series page 96 Initial issue, Jan. 01/2002...

  • Page 97: 12) Gearbox Components Check

    Clean and demagnetize the part. The maximum admissible remaining magnetism must not exceed 1,2 A/cm. Register the results of the magnetic particle inspection in the respective Form Sheet, see para 16.3. Effectivity: 912 Series page 97 Initial issue, Jan. 01/2002...
  • Page 98 Check dimension y of the released disk spring. See para 15. dimensions new mm (in.) wear limit mm (in.) See Dimension Sheets in para 15. fig. 153 41 ø 80 ø fig. 154 00271 00269 Effectivity: 912 Series page 98 Initial issue, Jan. 01/2002...

  • Page 99: 13) Propeller Gearbox Refitting

    ® NOTE: Apply LOCTITE Anti-Seize on the contact surfaces of the disk springs, on the dogs and the tooth profile of the propeller shaft. Effectivity: 912 Series page 99 Initial issue, Jan. 01/2002...

  • Page 100: 14) Disk Spring Pre-Tension Adjust

    14.4.10. CAUTION: Never depress springs completely, otherwise the dog gear will damage the gear cover. The ring halves must be completely inserted in the groove on propeller shaft! 04961 fig. 157 Effectivity: 912 Series page 100 Initial issue, Jan. 01/2002...

  • Page 101: 15) Propeller Gearbox Installation

    By gently tapping on the gear cover with a plastic mallet (not on propeller shaft) the gearbox is fitted on crankcase. Effectivity: 912 Series page 101 Initial issue, Jan. 01/2002...
  • Page 102 Remove crankshaft locking screw and screw in crankshaft plug screw with Cu sealing ring and tighten to 22 Nm (195 in.lb). For inspection turn crankshaft with wrench 24 a/f on hex. screw on magneto side. 00274 fig. 159 12 13 Effectivity: 912 Series page 102 Initial issue, Jan. 01/2002...

  • Page 103: Cylinder Head Removal

    Lay aside push rods, coordinated to cylinder heads by numbers to avoid any mix up at reassembly. fig. 161 Effectivity: 912 Series page 103 Initial issue, Jan. 01/2002...

  • Page 104: Cylinder Head Disassembly

    Allow cylinder head to cure for approx. 10 minutes at 80° C (176° F). Carbon deposits on the sealing surface to the cylinder, should be removed carefully with lapping fleece or solvent. Effectivity: 912 Series page 104 Initial issue, Jan. 01/2002...

  • Page 105: 2) Valve Guides

    15. At presence of burned spots or deformation, send cylinder head for overhaul to an authorized overhaul facility. dimensions new mm (in.) wear limit mm (in.) See Wear Limits in para 15. Effectivity: 912 Series page 105 Initial issue, Jan. 01/2002...

  • Page 106: Valves

    In design year 1997 the single spring retainer was introduced, see SI-14-97. NOTE: Actual spring length should be as equal as possible, on inlet and outlet side. Renew as required. Dimensions Wear limits See Wear Limits in para 15. Effectivity: 912 Series page 106 Initial issue, Jan. 01/2002...

  • Page 107: 6) Rocker Arm

    Check hardness in the area T of the bear- ing support. For minimum hardness, see Wear Limits in para 15. Do not damage sealing surface for O-ring 6,4 x 1,8 Y. 04315 fig. 211 Effectivity: 912 Series page 107 Initial issue, Jan. 01/2002...

  • Page 108: 8) Cylinder Heads Reassembly

    11.7.18. NOTE: The rocker arm shaft must slide easily into the bore. Do not apply force! Lubricate all internal parts with motor oil and check for easy movement., see para 11.7.1. Effectivity: 912 Series page 108 Initial issue, Jan. 01/2002...

  • Page 109: Cylinder And Piston Disassembly

    O until the piston P can be removed. Remove nut U and the puller ass´y. fig. 173 Coordinate piston pin to keep each piston pin with its respec- tive piston for reassembly. 00290 00291 fig. 174 Effectivity: 912 Series page 109 Initial issue, Jan. 01/2002...

  • Page 110: Piston Check

    14.6.1) Piston check See fig. 175 and 176. The engine type 912 Series has cast light alloy, full skirt pistons. The piston axis is offset by 1 mm (.039 in.). Remove piston rings using a pair of piston ring pliers.

  • Page 111: 2) Piston Rings Check

    Ölabstreifring / fig. 179 oil scraper ring 00295 14.6.3) Dimensions of pistons and piston rings See fig. 175, 177, 178 and 179. Dimensions Wear limits See Wear Limits in para 15. Effectivity: 912 Series page 111 Initial issue, Jan. 01/2002...

  • Page 112: Piston Pin

    True up cylinder and cylinder head by lapping the mating surfaces with lapping paste (e.g. valve lapping paste or equivalent) until required sealing is achieved. 00298 fig. 180 fig. 181 00297 Effectivity: 912 Series page 112 Initial issue, Jan. 01/2002...

  • Page 113: Hydraulic Valve Tappets

    Check push rods supported on V-blocks for straightness, see dim. G. Through the bores E oil passes from the valve tappet to the rocker arm. 00302 fig.185 Effectivity: 912 Series page 113 Initial issue, Jan. 01/2002...

  • Page 114: Displacement Parts Reassembly

    187 Zylinder 1 und 3 / Zylinder 2 und 4 / auf den Propellerflansch gesehen / Cylinder 1 and 3 Cylinder 2 and 4 looking at propeller flange 00305 fig. 188 Effectivity: 912 Series page 114 Initial issue, Jan. 01/2002...
  • Page 115 Always use new piston pin circlips! Used or circlips already fitted once exert insufficient tangential force thus allowing circlips to turn with consequent wear of the circlip groove. fig. 190 04706 12 14 02038 fig. 191 Effectivity: 912 Series page 115 Initial issue, Jan. 01/2002...

  • Page 116: 3) Fitting Of Cylinder

    2 collar cap nuts M8 and 2 hex. nuts M8 along with washers, tightening slightly only! Pay attention for squeezing O-rings W evenly into crankcase. Repeat same procedure, if necessary, on the cylinder heads. 00278 fig. 193 Effectivity: 912 Series page 116 Initial issue, Jan. 01/2002...
  • Page 117 Screw in resistance spark plugs and tighten to 20 Nm (180 in.lb). Fit spark plug connectors according to cod- ing sleeves on spark plugs, see para 13.4.11. 00312 NOTE: Proceed as per Wiring Diagram. fig. 195 Effectivity: 912 Series page 117 Initial issue, Jan. 01/2002...

  • Page 118: Fitting Of Coolant Hoses

    If instead of the Allen screw and the spacer a cheese head screw is fitted the support kit part no. 887.730 (fig. 198) has to be used. Same procedure with the 2nd carburetor. Effectivity: 912 Series page 118 Initial issue, Jan. 01/2002...

  • Page 119: Connecting Of The Fuel Lines

    CAUTION: At tightening of joints on the fuel lines do not apply any forces or moments on fuel pump connections and prevent bending of the connecting tubes. Refer to para 13.1.6. Effectivity: 912 Series page 119 Initial issue, Jan. 01/2002...

  • Page 120: Wear Limits Sheets

    AIRCRAFT ENGINES MAINTENANCE MANUAL II 15) Wear limits sheets 15.1) Wear limits for ROTAX 912 UL/A/F ® Designation wear limit actual dim. (in.) (in.) int. / exh. Cylinder/Piston see para 16.1 Form sheets Piston pin piston pin bore ........20,001÷20,005 (0,7874 ÷ 0,7876) ..20,04 (0,789) ......
  • Page 121 9 ....0,1 ÷ 0,2 (0,004 ÷ 0,008) ..0,3 (0,012) ......Push rod out of round G ........0,0 ÷ 0,1 (0,0 ÷ 0,004) ..0,2 (0,008) ......Effectivity: 912 Series page 121 Initial issue, Jan. 01/2002...

  • Page 122: Wear Limits For Rotax 912 S/Uls

    AIRCRAFT ENGINES MAINTENANCE MANUAL II 15.2) Wear limits for ROTAX 912 S/ULS ® Designation wear limit actual dim. (in.) (in.) int. / exh. Cylinder/Piston see para 16.1 Form sheets Piston pin see para 15.1 Piston rings compression ring see para 15.1 ring end gap F ........

  • Page 123: Form Sheets

    AIRCRAFT ENGINES MAINTENANCE MANUAL II 16) Form Sheets 16.1) Form Sheet for Cylinders and Pistons for ROTAX 912 UL/A/F/ULS/S ® Protocol for Maintenance Form Sheet no. 17-036/E—00 10 18 AIRCRAFT ENGINES Form Sheet 3 ROTAX for engine no.: Cylinder and piston position...

  • Page 124: Form Sheet For Ext. Generator

    AIRCRAFT ENGINES MAINTENANCE MANUAL II 16.2) Form sheet for ext. generator fig. 209 04727 Effectivity: 912 Series page 124 Initial issue, Jan. 01/2002...

  • Page 125: Form Sheet For Crack Inspection

    Magnetnabe / Magneto flywheel........_______________________________ _______________________________ Nockenwelle / Cam shaft....HV 10 min.680 ...._______________________________ _______________________________ Prüfer / Tester ________________ Datum / Date ___________ Abt./ Dept.: _____________________________ fig. 208 Vert.: Halter/Owner 04728 Effectivity: 912 Series page 125 Initial issue, Jan. 01/2002...

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912 ul912 a912 f912 s912 uls

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