D-MOTOR LF26 User manual

The Light Weight Engine Houtekietstraat 11
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D-MOTOR International © AIRCRAFT ENGINE
ENGINE OWNERS MANUAL
TYPE LF26 - 4 Cylinder Engine
Publication : 2019.3/LF26
© D-Motor International bvba, February 2019

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Succession Notice
This manual is a revision of the previous manual published in 2013 and any revisons there of. Information within this document
replace the instructions of previous D-Motor International Publications –Engine Owners Manual.
Effective Changes for this manual / document
February 2019 V1
August 2019 v3 (KGhekiere)
March 2019 V2
November, 2019 V3 (KGhekiere)
Published and printed in Belgium by D-Motor International, bvba.
Copyright ©2013,2015,2019 D-Motor International, bvba.
All rights reserved.
This material may not be reprinted, republished, broadcast, or
otherwise altered without the publisher's written permission. This manual is provided without
express, statutory, or implied warranties. The publisher will not be held liable for any damages
caused by or alleged to be caused by use, misuse, abuse, or misinterpretation of the contents.
Content is subject to change without notice. Other products and companies mentioned herein
may be trademarks of the respective owners.

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Contents
Blank Page (intentional) .......................................................................................................................... 5
INTRODUCTION ....................................................................................................................................... 6
D-MOTOR Engines.............................................................................................................................. 6
SCOPE AND PURPOSE OF THIS DOCUMENT........................................................................................ 6
Warning............................................................................................................................................... 7
Advisories ............................................................................................................................................ 7
Order of Precedence ........................................................................................................................... 7
Updates/Changes Distribution............................................................................................................ 8
Suggestions and corrections ............................................................................................................... 8
Contact Information............................................................................................................................ 8
TOA (Table of Amandments)............................................................................................................... 9
SAFETY INFORMATION.......................................................................................................................... 10
MAIN SECTION....................................................................................................................................... 11
Technical Sheet LF26 type D-Motor Engine ...................................................................................... 11
Operating limits............................................................................................................................... 13
Description ........................................................................................................................................ 15
ENGINE OPERATION.......................................................................................................................... 19
Engine start.................................................................................................................................... 19
Motor STOP ................................................................................................................................... 21
ENGINE Checking........................................................................................................................... 21
Emergency Procedures.................................................................................................................. 22
ECU ERROR MESSAGES.................................................................................................................. 24
Safety / Avoiding failures .............................................................................................................. 25
Loss of Cooling liquid.................................................................................................................... 25
Oil Supply....................................................................................................................................... 26
Throttle adjustments..................................................................................................................... 27
Fuel Supply .................................................................................................................................... 28
Important Information about fuels and lubricants : ..................................................................... 29
Power Supply................................................................................................................................. 30
Control and function test of the power supply............................................................................. 30
Spark plugs .................................................................................................................................... 31
TABLE FOR TORQUE VALUES......................................................................................................... 31
Performance Curve of the LF26 Engine......................................................................................... 34
Periodic inspections .......................................................................................................................... 35

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First 25 & 50-hour-inspection ....................................................................................................... 35
100-hour-inspection or annually................................................................................................... 35
200-hour-inspection...................................................................................................................... 35
Preservation of the engine for long term storage............................................................................. 36
Winter operation............................................................................................................................... 37
Care of the electrical system......................................................................................................... 37
Cold starting procedures............................................................................................................... 37
TROUBLE SHOOTING ......................................................................................................................... 37
Engine does not fire ...................................................................................................................... 37
Warm engine shows irregular idling ............................................................................................. 38
Engine runs erratic or misfires occasionally.................................................................................. 38
Engine overheats, Oil temperature over 100 deg.C (212 deg.F)................................................... 38
The engine does not develop full power....................................................................................... 39
Low oil pressure ............................................................................................................................ 39
The engine does not stop immediately......................................................................................... 40
Excessive oil consumption............................................................................................................. 40
Engine « knocks ».......................................................................................................................... 40
Engine hard to start at low temperatures..................................................................................... 40
OVERHAULS....................................................................................................................................... 41
Major inspections at TBO.............................................................................................................. 41
Major repairs and major modifications......................................................................................... 41
ENGINE REGISTRATION CARD –WARRANTY ACTIVATION................................................................ 42
Checklist parts ................................................................................................................................... 43
Blank Page (intentional) ........................................................................................................................ 48

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Blank Page (intentional)

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INTRODUCTION
D-MOTOR Engines
D-Motor LF 26 4 cylinder and LF39 6 cylinder engines are direct drive 100% water cooled boxer side
valve engines. The engines incorporate multi-point fuel injection controlled by an advanced twin ECU
control system which is performance mapped with Lambda sensing.
A 300W/25A generator is fully integrated as standard fitment; the oil and coolant pumps are directly
driven by the camshaft. The fuel pressure is held at a constant level with a pressure regulator, which
is connected to the fuel recirculating system. Air inlet preheating is not required and not installed.
The entire motor is controlled and monitored by the ECU (Electronic Control Unit). A second ECU is
standard, battery and fuel pump can be installed as a redundant system.
D Motor aircraft engines are a Premium Quality European Product designed and produced in Belgium
https://www.d-motor.eu
SCOPE AND PURPOSE OF THIS DOCUMENT
This manual gives instruction and guidance for engine preparation, installation, and operation of the
LF26 and LF39 aircraft engines. The installation instructions within this manual are basic guidelines.
When installing the engine in the airframe, follow the airframe manufacturer’s installation
instructions. Refer to the D-Motor Engine Service and Installation manual for required maintenance
(service information) such as: oil changes, oil top up, oil filter replacement, routine time limited-
interval inspections, routine service, spark plug replacement/inspection procedures, cylinder
inspection, fuel system inspection, and scheduled servicing procedures. For airworthiness limitations,
guidelines to fault finding and for procedures to replace components, disassembley and re-
assembley of the engine, refer to the D-Motor Engine Maintenance Manual. For spare parts
information, refer to the D-Motor Illustrated Parts Catalog.

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Warning
This is a non-certified aircraft engine ; the possibility of engine stoppage exists at all times. Do not
operate this engine over densely populated areas. Do not operate this engine over terrain where a
safe, power off landing cannot be performed.
The operation and maintenance instructions supplied with this engine must be followed at all times.
Flying any aircraft involves the risk of injury or death, building and maintaining your own aircraft
requires great personal responsibility.
Advisories
This document utilizes three types of advisories; defined as follows:
WARNING
A warning emphasizes information which, if disregarded, could result in severe injury to
personnel or equipment failure.
CAUTION
Emphasizes certain information or instructions, which if disregarded, may result in damage to
the engine or accessories.
NOTE
Provides special interest information, which may facilitate performance of a procedure or
operation of equipment.
Warnings and cautions precede the steps to which they apply; notes are placed in the manner which provides the greatest
clarity. Warnings, cautions, and notes do not impose undue restrictions. Failure to heed advisories will likely result in the
undesirable or unsafe conditions the advisory was intended to prevent. Advisories are inserted to ensure maximum safety,
efficiency, and performance. Abuse, misuse, or neglect of equipment can cause eventual engine malfunction or failure.
Order of Precedence
WARNING

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The aircraft operator must use the airframe manufacturer’s operating instructions found in the Airplane Flight Manual/
Pilot’s Operating Handbook (AFM/POH) while operating the aircraft unless the AFM/POH directs otherwise.
Updates/Changes Distribution
Document updates are available from our web site upon notification of official document approval.
Printed publication subscribers receive printed changes and revisions as they are released.
Document revisions are released if the update changes more than 50% of the contents of a
publication. Revisions replace the previous version of a publication from cover to cover.
Minor corrections are released as change pages to the original publication, identified with a change
number and effective change date in the page footer. Information on the page that changed from
the previous edition is identified by a vertical, six-point black line referred to as a “change bar” in the
outside margin of the page. A page change replaces only the previous edition of the affected page.
Suggestions and corrections
D-Motor International solicits and encourages user comments regarding suggested changes to this
manual. Direct recommended changes or questions to the attention of “Publications” at the address
listed in this section, “Contact Information” or send comments via e-mail to [email protected]. Notify
our Customer Service Department immediately, using our telephone number, if you discover
incorrect information which adversely affects safety !! Thank you !!
Contact Information
D-Motor International factory representatives are available to answer technical questions and
encourage suggestions regarding products, parts, or service. If customers have an inquiry or require
technical assistance, they should contact their Regional D-Motor Dealer/Distributor or Field
Representative. To contact a Factory Representative, refer to the contact information below:
D-Motor International, bvba
Houtekiestraat 11
B-8540 DEERLIJK

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BELGIUM
Customer service department : [phone]
[e-mail] https://www.d-motor.eu
TOA (Table of Amandments)
Current
N°
Chapter
Page
Change
date
Remark
Date
approval
Date
inclusion
Signature
0
0
INTRO
Before operating the engine, carefully read this Operators Manual.
This Manual provides you with basic information on the safe operation of the D Motor engine. If any
sections of the Manual are not clearly understood or if you have any questions, please contact a D-
Motor International® authorized aircraft engines Dealer/Distributors or their Independent Service
Center. D-Motor International wants to ensure your satisfaction, flying your aircraft powered by this
D-Motor®-aircraft engine.

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SAFETY
INFORMATION
! WARNING : Never operate the aircraft equipped with a D-Motor at locations, airspeeds,
altitudes, Or other circumstances from which a succesful no-power landing cannot
be made, after sudden engine failure (stoppage).
•The D-Motor engine is not suitable for acrobatics.
•The selection and use of the D-Motor on any aircraft is at the sole discretion and
responsibility of the aircraft manufacturer, assembler and owner or user.
•Duet o different designs, equipment and types of aircraft, D-Motor will allow no warranty or
representation on the suitability of its engine’s use on any particular aircraft. Furthermore,
D-Motor grants NO warranty or representation of its engine’s suitability with any other part,
component or system which may be selected by the aircraft manufacturer, assembler or user
for aircraft application.
•Whether you are a certified pilot or a student, complete knowledge of the aircraft, its
controls and operation is mandatory before flying solo. Flying any type of aircraft involves a
certain risk! As user or owner of a D-Motor engine, be informed and prepared for any
situation or hazard associated with flying.
•Make sure that you also obtain as much information as possible about your aircraft and
engine (Service and Information Bulletins), their maintenance and operation from your
dealer!
•Be aware that our engines may seize or stall at any time! This could lead to crash landing and
possible severe injury or death. D-Motor recomments strict compliance with the
maintenance and operation and any other information which may be given to you by your
dealer or was published on the D-Motor website (https://www.d-motor.eu)
•Fly only when and where conditions, topography, and airspeeds are the safest !
•Use proper aircraft instrumentation. D-Motor does not deliver this instrumentation!
•Always ensure BEFORE FLIGHT that all engine controls are operative. Make sure that all
control scan be reached in case of an emergency.
•Always run the engine and propellors in a bystander clear area !
•DO NOT leave the aircraft unattended with the D-Motor engine running !
•Keep a engine LOGBOOK and respect the engine and aircraft maintenance windows. KEEP
YOUR D-MOTOR ENGINE IN TOP OPERATING CONDITIONS AT ALL TIMES.

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•When in storage protect the engine and fuel system from contamination and exposure.
•NEVER operate the LF26/39 engine without OIL or Water, NEVER with insufficient OIL or
WATER !
•Periodically verify level of coolant.
•Never exceed maximum rated RPM. Allow your D-Motor engine to cool at idle for several
minutes before turning off the engine.
MAIN SECTION
Technical Sheet LF26 type D-Motor Engine
Producer D-Motor, Belgium
Construction 4 cylinder boxer motor, four stroke, side valve
Reduction gear Direct drive
Cooling fully liquid cooled
Control unit ECU –12 V
8A for ECU and fuel pump required
Intake Multipoint sequential fuel injection
Ignition Double CDI, controlled by ECU
Generator 300 W/25A integrated
Bore 103.6 mm
Stroke 80 mm
Displacement 2.697 cc
Compression 8,0
Starter 12V - 1.1 KW
Fuel pressure 2.5 –3.0 bar (36 to 43psi)
Fuel regulator 2.5 bar (36psi) opening pressure in the recirculation system
Fuel MOGAS Super Unleaded 95 OCT, UL91
Fuel filter Ultra-fine fuel filter mounted on the pressure side of fuel
pump
P/N 107201
Power 69 kW (94hp) at 3.000 RPM

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Torque 220 nm (162 ft/lbs) at 2.600 RPM
Rage of use 800 to 3000 RPM
2100 RPM to 2800 RPM in Cruise
Lubrication Dry sump
Oil pump Pump driven by camshaft
Oil pressure 1.5 - 5.0 bar (21 to 75psi)
Oil specification Synthetic 5W50 - 5W40 (Cold weather 0W50 –0W40 )
Oil quantity 2.5 Litre (4 ½ pints) (exc. hoses, etc)
Oil filter D Motor (P/N 107001)
Oil temperature min 50° C to 100° C (122 to 212 f)
80°C to 100°C (176 to 212 f) best range
Coolant liquid 50/50 deionised water with anticorrosive
(for Aluminium motors)
Coolant liquid temperature 50°C to 100°C (max 212 F°) (opening pressure at 1.2 bar 17psi)
See Service Bulletin 2019-15 or newer
Cooling liquid pump pump driven by camshaft
Propeller flange bolt-hole circle dia. 101.6 mm 6 x 13mm
Spark plug P/N 106021
Ignition coil P/N 106031
Plug cap 90° angled, rubberized
Lambda probe P/N 185001

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Operating limits
Performance
only to be insured if with consideration of the following :
* Standard engine
* without auxilary equipment
* ISA condition
* installation following installation guidelines
Take –Off performance
70 KWatt / 95 HP at 3.000 RPM
Maximum continious performance
67.5 KWatt / 92 HP at 2.800 RPM
Speed
Take –Off speed
3.000 RPM (max. 5 min)
Maximum continious speed
2.800 RPM
Idle speed
Min 1.000 RPM
Acceleration - limit of engine operation at zero Gravity and in negative G condition
Maximum
5 seconds at max -0.5 G
Oil pressure
Normal
1.5 to 4.5 bar / 21 psi to 65 psi
Maximum
5 bar / 75 psi
Minimum
0.8 bar / 11 psi
Oil temperature
Normal
80°C –100°C (176°F –212°F)
Maximum
100°C (212°F)
Minimum
50°C (122°F)

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Coolant temperature
Maximum
100°C –212°F
Ambient temperature
Maximum in flight
60°C (140°F) (MAP temperature)
Maximum at start
45°C (113°F) ambient temperature
Minimum at start
-20°C (-13°F) (oil temperature)
Fuel pressure
Maximum
3.0 bar (43psi)
Minimum
2.5 bar (36psi)
Bank Angle
Maximum
40°
NOTE : up tot his value the lubrication system
warrants lubrication in every flight situation.
LF 26 type ENGINE

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Description
D-Motor LF 26 4 cylinder and LF39 6 cylinder engines are direct drive 100% water cooled boxer side
valve engines. The engines incorporate multi-point fuel injection controlled by an advanced twin ECU
control system which is performance mapped with Lambda sensing.
A 300W/25A generator is fully integrated as standard fitment; the oil and coolant pumps are directly
driven by the camshaft. The fuel pressure is held at a constant level with a pressure regulator, which
is connected to the fuel recirculating system. Air inlet preheating is not required and not installed.
The entire motor is controlled and monitored by the ECU (Electronic Control Unit). A second ECU is
integral within the ECU housing as standard, a secondary battery and fuel pump can be installed as a
redundant system.

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During the operation of the engine the following data and information are constantly collected,
analysed and interpreted by the ECU
•Throttle position
•Intake air temperature
•Crankshaft position analogue
•Crankshaft position digital
•Air and manifold pressure
•Coolant temperature
•On-board power supply voltage
•RMP
•Lambda probe values
Should one of the sensors fail, the ECU will automatically revert to a standard or emergency program,
in this configuration the will motor continue to run, but with reduced power output and increased fuel
consumption. The ECU signals its status by means of LEDs on the ECU Casing, or optionally by means
of a separate monitor.
As the option of a redundant system is installed by default(by the ECU, Battery and Fuel pump, etc.)
the redundant systems controls themselves reciprocally. The full operation is still assured if one circuit
fails totally

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Due to the side valve design of the motor, some motor failures normally found with OHV engines (for
example valve tearing will not stop the motor from functioning). Inflight even the loss of one or two
cylinders can be compensated for and the motor continues to run with less power, which allows time
for a safety landing.
The electrical supply is very important for a safe operation of the motor, should the generator fail and
the battery is not charged sufficiently , the motor will continue to run only until the minimum power
supply voltage of 8V is reached. Installation in the electric system of a sufficiently sized capacitor will
ensure continued operation of the engine in the case of a battery failure.
Short specification list
•Type: D- motor LF26
•Class: Microlight aircraft
•Engine: Four cylinder, four stroke, liquid cooled
•Displacement: 2690 cc
•Stroke: 80 mm
•Compression ratio: 8/1
•Max power: 69 kW (94hp) at 3000 RPM
•Max continuous power: 65.3KW (88.8 hp) at 2800 RPM
•Used fuel: 91, 93, 95. 98 octane or avgas
•Fuel consumption: see fuel consumption table
•Maximum torque: 220 Nm (162 ft/lbs) at 2500 RPM
•Intake: Multipoint sequential fuel injection
•Alternator: 25 Amp integrated
•Electric starter: 1.1 KW integrated
•Ignition: Double

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•Installed dry weight (liquids 5kg): 58 kg (127lbs) (battery and liquids not included)
WARNING !!
DUE TO THE PRECISION OF THE ECU CRANKSHAFT ROTATION
MEASUREMENT
IT IS POSSIBLE TO HAND START THE LF26 BY ROTATING THE PROPELLER.

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ALWAYS ENSURE ALL SWITCHES ARE OFF BEFORE WORKING ON
THE LF26 ENGINE.
ENGINE OPERATION
Engine start
The LF 26 does not have a choke or hot air intake. Thanks to the twin ECU and multipoint fuel injection
system the motor may be started at any temperature without any special precaution.
The handling of the engine is based on following elements:
•Master switch Activate starting system
•Start Button Activate the starter
•ECU Fuse/Switch ON/OFF switch for the ECU with fuse function

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•Fuel pump Fuse/Switch ON/OFF switch for the fuel pump with fuse
function
•Ignition circuit (2x) ON/OFF switches of the ignition circuits (mag switches)
•Throttle Regulate the power setting
After the pre-flight check and provided the propeller area is free the motor can be started:
•Turn on Master Switch
•Fuel pump - ON
•Both ignition circuits - ON
•ECU –ON (if the outside air temperature is low the ECU may be switched 2 or 3 times ON and OFF
in order to enrich the fuel injection and ease the starting procedure.
•Throttle set on idle position.
•Push the starter button until the motor starts. Try for maximum 10 seconds, and then stop the
starting process. Wait 30 seconds and try again to start the motor.
•As soon as the motor runs increase the RPM after a few seconds
•Switch on the monitoring instruments and check the oil pressure
•Warm up with about 1200 RPM
If the oil pressure is insufficient or in case of an error message from the ECU, stop the engine
immediately and if necessary investigate for the problem.
If no error is reported and the oil pressure is sufficient warm-up the motor until the oil and water
reach 50°C (122 f).
Check both ignition circuits before take-off. To do so increase the power setting up to 2000 RPM and
switch OFF circuit 1 for 5 seconds, monitor the RPM which shouldn’t change for more than 50 RPM.
Repeat with circuit 2. The difference between the RPM drop while checking both circuits shouldn’t
exceed 30 RPM.
While checking both circuits, as soon as one circuit is switched OFF the ECU should report this error by
means of a flashing LED or by the corresponding text message on the engine monitory instrument.
CAUTION!
Never start the engine without prop installed. Otherwise the engine
will be damaged.