D-MOTOR LF39 User manual

The Light Weight Engine Houtekietstraat 11
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D-MOTOR International © AIRCRAFT ENGINE
ENGINE OWNERS MANUAL
TYPE LF39 - 6 Cylinder Engine
Publication : LF39_2019_2
© D-Motor International bvba, March 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 (KGhekiere)
March 2019 V2 (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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Inhoud
Blank Page (intentional) 5
INTRODUCTION 6
D-MOTOR Engines 6
SCOPE AND PURPOSE OF THIS DOCUMENT 6
Warning 7
Advisories 7
Order of Precedence 8
Updates/Changes Distribution 8
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 8
Suggestions and corrections 8
Contact Information 9
TOA (Table of Amandments) 10
SAFETY INFORMATION 11
MAIN SECTION 12
Technical Sheet LF39 type D-Motor Engine 12
Description 15
Center Of Mass (CG) 20
ASSEMBLY SHORT PROPELLOR FLANGE 21
HANDLING OF THE ENGINE 21
Motor START 21
The handling of the motor is based on following elements 21
After the pre-flight check and provided the propeller area is free the motor is started 22
Motor STOP 23
ENGINE Checking 23
Emergency Procedures 25
ECU ERROR MESSAGES 26
Safety / Avoiding failures 27

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Loss of Cooling liquid 27
Oil Supply 28
Throttle adjustments. 29
Fuel Supply 30
Important Information fuels and lubricants : 31
Water Pump 32
Power Supply 33
Control and function test of the power supply 33
Spark plugs 34
Performance Curve of the LF39 Engine 36
Periodic inspections 37
First 25 & 50-hour-inspection 37
100-hour-inspection or annually 37
200-hour-inspection 38
Preservation of the engine for long term storage 38
Winter operation 38
TROUBLE SHOOTING 39
Engine does not fire 39
Warm engine shows irregular idling 39
Engine runs erratic or misfires occasionally 40
Engine overheats, Oil temperature over 100 Deg.C (212 deg.F) 40
The engine does not develop full power 41
Low oil pressure 41
The engine does not stop immediately 41
Excessive oil consumption 42
Engine « knocks » 42
Engine hard to start at low temperatures 42
OVERHAULS 43
Major inspections at TBO 43
Major repairs and major modifications 43
Water and Oil 44
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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.

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Order of Precedence
WARNING
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 !!

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Contact Information
D-Motor International factory representatives are available to answer technical questions and
encourages suggestions regarding products, parts, or service. If customers have an inquiry or require
technical assistance, they should contact their local 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
BELGIUM
Customer service department : [phone]
[e-mail] https://www.d-motor.eu

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TOA (Table of Amandments)
Current N°
Chapter
Page
Change
date
Remark
Date
aproval
Date
inclusion
Signature
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0
INTRO
Before operating the engine, carefully read this Operators Manual. The Manual provides you with
basic information on the safe operation of the engine. If any passages of the Manual are not clearly
understood or in case of any questions, please contact an D-Motor International® authorized aircraft
engines dealer/distributors or their independent service center. D-Motor International wishes you
much pleasure and 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.
•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 coll at idle for several
minutes before turning off the engine.

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MAIN SECTION
Technical Sheet LF39 type D-Motor Engine
Producer D-Motor, Belgium
Construction 6 cylinder boxer motor, 4 stroke
Reduction gear Non
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 103.5 mm
Stroke 80 mm
Displacement 3.900 cc
Compression 8.1/1
Starter 12V - 1.1 KW integrated
Fuel pressure 2.5 –3.0 bar (36.2 –43.5 PSI)
Fuel regulator 2.5 bar (36.2 PSI) opening pressure, in the back flow
Fuel MOGAS Super leadless 95 ROZ, or AVGAS
Fuel filter P/N 107201
Ultra-fine filter, pressure side operated
Fuel pump Pressure 3.0 bar (43.5 PSI) 130 L/h flow
Power 125 HP at 3.100 RPM
Torque 283 Nm at 2.500 RPM
Rage of use 800 to 3100 RPM
2100 u/min to 2800 u/min in Cruise
Lubrication Dry sump
Oil pump Pump driven by camshaft
Oil pressure 1.5 - 5.0 bar (21.7 –72.5 PSI)

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Oil specification Synthetic 5W50 - 5W40 - 0W50 –0W40
Oil quantity 3.5 Liters (0.91 US Gallons)
Oil filter P/N 107001
Oil temperature min 50° C to 120° C
80°C to 100°C best range
Cooling liquid Water with antifreeze and anticorrosive
(for Aluminium motors)
Cooling liquid temperature 50°C to 100°C (opening pressure at 1.2 bar)
See Service Bulletin 2019-015
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 90° angled, rubberized
Lambda probe P/N 185001

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LF 39 type ENGINE (exploded)

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Description
The D-Motor LF 39 is a 100% water cooled boxer motor with side steered valves for direct driven
propellers. The motor has a lambda probe and performance map controlled multi field injection with
double ignition. The 300W/25A generator is fully integrated; the oil and cooling liquid pumps are
directly driven by the camshaft. The fuel pressure is hold at a constant level by a pressure regulator,
which is connected to the back flow circuit. An intake air preheating is not required and not installed.
The entire motor is controlled and surveyed by the ECU (Electronic Control Unit). Standard is a
redundant second ECU, battery and fuel pump and is installed as a redundant system.
During the use of the motor following data and information are constantly collected, analysed and
interpreted by the ECU
•Throttle valve position
•Intake air temperature
•Crankshaft position analogue
•Crankshaft position digital
•Air pressure
•Cooling liquid temperature
•On-board power supply voltage
•RPM
•Lambda probe values
If one of the sensors fails, the ECU change into a standard or emergency program, in which the motor
continues to run, but eventually with less power and increased consumption. The ECU signalizes 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.
Due to the sidesteered design of the motor, some motor failures (for example valve tearing) wouldn’t
stop the motor to work. Inflight even a loss of one or two cylinders can be compensated and the
motor continues to run with less power, which enables to initialize a safety landing.
The power supply is very important for a safe operation of the motor. Should the generator fail and
the battery is not charged sufficiently anymore, the motor continues to run only until the minimum
power supply voltage of 8V is reached.

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The above is one option, please contact our sales team for all possible options, incl. heli options.
Short specification list
•Type: D- motor LF39
•Class: Microlight aircrafts
•Engine: 6 cylinders, four stroke, liquid cooled
•Displacement: 3993 cc
•Stroke: 79 mm
•Compression ratio: 8/1
•Max power: 125 Hp at 3000 RPM
•Max continuous power: 112Hp hp at 2800 RPM
•Used fuel: 91, 93, 95 oct. 98 oct. or avgas
•Fuel consumption: 19 liter at 75% performance
•Maximum torque: 285 Nm at 2500 RPM
•Intake: Multipoint sequential fuel injection
•Alternator: 25 Amp integrated
•Electric starter: 1.1 KW integrated
•Ignition: Double
•Installed dry weight (liquids 7kg): 78 kg

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Accessories
Delivered with standard engine package:
•The engine with integrated alternator, water pump, oil pump and electric starter.
•Rubber mounts (dimensions same as Jabiru and UL power).
•Fuel pump, fuel filter and injectors.
•2 ignition coils, spark plugs and ignition leads.
•ECU and loom (standard redundant injection).
•3 water temperature sensors (2 for ECU and one for instrument).
•Oil pressure and oil temperature sensor.
•Oil filter, oil tank with breather system.
•Exhaust pipes included and lambda probe, no mufflers are included.
•The liquid cooling system (radiator, hoses and expansion tank) are not included.
The different aircraft and helicopters, equipped, required different cooling configurations. It is
difficult to anticipate a solution for every installation. Attempting to provide a universal solution
would be both inefficient and overly expensive.
The weight of the engine completely installed with liquids is 85 and 88 kg depending on installation.
This weight does not include the engine mount or propeller.
The TBO time is 1500 hours.
Options:
•Rajapack crate , packaging and handling
•Warranty: 2 year

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WARNING !!
DUE TO THE PRECISION OF THE ECU CRANKSHAFT ROTATION
MEASUREMENT
IT IS POSSIBLE TO HAND START THE LF39 BY ROTATING THE PROPELLER.
ALWAYS ENSURE ALL SWITCHES ARE OFF BEFORE WORKING ON THE LF39
type ENGINE.

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Center Of Mass (CG)