# Rotax 912

The Rotax 912 is a horizontally-opposed four-cylinder, naturally-aspirated, four-stroke aircraft engine with a reduction gearbox. It features liquid-cooled cylinder heads and air-cooled cylinders. Originally equipped with carburetors, later versions are fuel injected. Dominating the market for small aircraft and kitplanes, Rotax produced its 50,000th 912-series engine in 2014. Originally available only for light sport aircraft, ultralight aircraft, autogyros and drones, the 912-series engine was approved for certified aircraft in 1995.

## Design and development

The Rotax 912 was first sold in 1989 in non-certificated form for use in ultralights and motorgliders. The original 60 kW (80 hp) 912 UL engine has a capacity of 1,211 cc (73.9 cu in) and a compression ratio of 9.1:1, and is designed to work with regular automotive gasoline, with up to 10% ethanol. The later certified 75 kW (100 hp) 912 ULS variant has a compression ratio of 11:1, and requires 91-octane ("premium") auto gas (100LL leaded avgas can be used, sparingly).
The engine differs from previous generation aircraft engines (such as the Lycoming O-235) in that it has air-cooled cylinders with liquid-cooled heads and uses a 2.43:1 PSRU reduction gearbox to reduce the engine's relatively high 5,800 rpm shaft speed to a more conventional 2,400 rpm for the propeller. The gearbox has proven to be generally trouble-free. On the 912A, F and UL the standard reduction ratio is 2.27:1 with 2.43:1 optional. Lubrication is dry sump, and fuelling is via dual CV carburetors or fully redundant electronic fuel injection. The electronic fuel injected Rotax 912iS is a recent development.
The 912's lubrication system differs from most dry-sump designs in that oil is forced into the storage tank by crankcase pressure rather than by a separate scavenge pump. This requires a novel preflight inspection procedure: before checking the oil level with the dipstick, the engine is "burped" by removing the oil filler cap and turning the propeller until a gurgling sound is heard, which indicates that all oil has been forced into the tank and the oil level can now be checked accurately.
The 912 is more fuel efficient and lighter than comparable older engines, e.g., Continental O-200, but originally had a shorter time between overhaul (TBO). On introduction, the TBO was only 600 hours, which was double that of previous Rotax engines but far short of existing engines of comparable size and power. The short TBO and lack of certification for use in factory-built type certificated aircraft initially restricted its worldwide market potential. However, the engine received US Federal Aviation Administration (FAA) certification in 1995, and by 1999, the TBO had increased to 1,200 hours; on 14 December 2009, the TBO was raised from 1,200 hours to 1,500 hours, or 1,500 hours to 2,000 hours, depending on serial number. In addition to the lower fuel consumption, the 912 is certified to run on automotive fuel (mogas), further reducing running costs, especially in areas where leaded avgas is not readily available. The 912 may be operated using leaded fuel, but this is not recommended as lead sludge tends to accumulate in the oil tank and reduction gearbox. Also, avgas is incompatible with the recommended synthetic oil which cannot hold lead in suspension; consequently, the use of leaded fuel mandates additional maintenance.
A turbocharged variant rated at 86 kW (115 hp), the Rotax 914, was introduced in 1996. In 1999, the 912S / ULS were introduced; enlarged to 1,352 cubic centimetres (82.5 cu in) with a compression ratio of 10.8:1, yielding 75 kW (100 hp). The 912S is certified, as are the A and F, which are used in the Diamond DA20, which is quite popular in Europe. The 912's popularity was greatly enhanced by the introduction of the light-sport aircraft category in Europe and the United States, which resulted in the introduction of many factory-built aircraft designed to fully exploit the engine's small size and light weight. The 75 kW (100 hp) versions are used in many light sport aircraft, such as the Zenith STOL CH 701 and the Tecnam P2002 Sierra. The 60 kW (80 hp) versions are sufficient to power the new generation of efficient motorgliders, such as the Pipistrel Sinus and the Urban Air Lambada. It is also fitted to some light twins, such as the Tecnam P2006T.
On 8 March 2012 the company displayed its 912 iS variant, a 75 kW (100 hp) version with fuel injection and an electronic engine management unit. The version weighs 63 kg (139 lb), which is 6 kg (13 lb) more than the standard 912S. The non-certified 912 iS targets the light sport and homebuilt aircraft market and 912 iSc will be certified. Production started in March 2012 and the engine has a 2000-hour recommended time-between-overhaul to start.
On 1 April 2014 the company announced its new 912 iS Sport upgrade with greater power and torque and reduced fuel consumption. A further derivative, the 100 kW (135 hp) Rotax 915 iS, was announced in July 2015.

### Rotax's warnings to flyers

Unusually for a manufacturer of small aero-engines, Rotax publishes extensive warnings in the owner's manual about both the certified and non-certified versions of the engine design. Pilots are cautioned that the 912 engine is not suitable for:
* use in situations where a safe landing cannot be made
* use in rotorcraft
* night flying (unless equipped with redundant electrical power), or
* aerobatics.
The manual states that Rotax gives no assurances that the engine is suitable for use in any aircraft, and that the engine may seize or stall at any time, which could lead to a crash landing. The manual adds that non-compliance with such warnings could lead to serious injury or death.

## Variants

The engine is available in the following versions; coloured cylinder head caps are used to easily identify the different horsepower ranges:

### 912 A#

    Certified to JAR 22, 60 kW (80 hp), with dual carburetors and electronic ignition. Black cylinder head caps

### 912 F#

    Certified to FAR 33, 60 kW (80 hp), with dual carburetors and electronic ignition. Black cylinder head caps

### 912 iS

    Uncertified, 75 kW (100 hp) with direct fuel injection and an electronic engine management unit. Green cylinder head caps

### 912 iSc

    Certified, 75 kW (100 hp) with direct fuel injection and an electronic engine management unit

### 912 iS Sport

    Uncertified, aluminum airbox, longer intake runners and eco-mode when operated below 97% power setting. Green cylinder head caps

### 912 iSC Sport

Green cylinder head caps

### 912 S#

    Certified to FAR 33, 75 kW (100 hp) with larger bore than 912A/F/UL, with dual carburetors and electronic ignition. Green cylinder head caps

### 912 UL#

    Uncertified, 60 kW (80 hp), similar to the 912A/F. Black cylinder head caps

### 912 ULS#

    Uncertified, 75 kW (100 hp), similar to the 912S. Green cylinder head caps

### 912 ULSFR#

    Uncertified French Authority specification. 75 kW (100 hp)
The # in the designation stands for:
* Shaft with flange for fixed pitch propeller, P.C.D. 100 mm
* Shaft with flange for fixed pitch propeller, P.C.D. 75 mm, P.C.D. 80 mm and P.C.D. 4 inches
* Shaft with flange for constant speed propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D. 4 inches and drive for hydraulic governor for constant speed propeller
* Shaft with flange for fixed pitch propeller P.C.D. 75 mm, P.C.D. 80 mm, P.C.D. 4 inches also can be fitted with an adaptor, drive and governor for a constant speed propeller.

## Applications

* 3I Sky Arrow
* 3Xtrim 3X55 Trener
* A2 CZ Ellipse Spirit
* Acrolite
* Advanced Aeromarine Buccaneer II
* Aero Adventure Aventura II & XLR
* AeroAndina MXP-150 Kimbaya
* AeroAndina MXP-158 Embera
* Aero & Tech Nexth
* Aero AT-3
* Aero Bravo Bravo 700
* Aero Bravo Sky Ranger
* Aerocomp VM-1 Esqual
* Aero Designs Pulsar
* Aeroflying Sensation
* Aero-Kros MP-02 Czajka
* Aeromobil 3.0
* Aeroprakt A-20
* Aeroprakt A-22
* Aeroprakt A-28 Victor
* Aeroprakt A-36 Vulcan
* Aeros-2
* Aeros Cross Country
* Aerosette MH-46 Eclipse
* Aerostar R40S Festival
* Aeros UL-2000 Flamingo
* Aeropilot Legend 540
* Aerospool WT9 Dynamic
* Aero Synergie J300 Joker
* Aero Synergie Jodel D20
* Airbet Girabet
* Airborne Edge
* Airborne XT
* Air Command Tandem
* Air Copter A3C
* Air Creation Clipper
* Air Creation Skypper
* Air Creation Tanarg
* Airflow Twinbee
* AirLony Skylane
* Airmak J4
* AirMax SeaMax
* Airo 1
* Airtrike Eagle 5
* Albaviation D24 MagicOne
* Alisport Yuma
* Alpi Pioneer 200
* Alpi Pioneer 300
* Alpi Pioneer 300 Kite
* Alpi Pioneer 400
* AMD Zodiac
* AAC Seastar Sealoon
* Anglin J6 Karatoo
* Antares MA-34
* Antonov T-2M Maverick
* Apollo Delta Jet
* Apollo Fox
* Apollo Jet Star
* Apollo Monsoon
* Apollo Racer GT
* Aquila A 210
* ARV Griffin
* ARV Super2 (aftermarket installation)
* ATEC 122 Zephyr 2000
* ATEC 212 Solo
* ATEC 321 Faeta
* Australian Aircraft Kits Hornet STOL
* Australian Lightwing GR 912
* Australian Lightwing SP-2000 Speed
* AutoGyro MT-03
* AutoGyro MTOsport
* AutoGyro Calidus
* AutoGyro Cavalon
* Avama Stylus
* Aveko VL-3 Sprint
* Aviadesign A-16 Sport Falcon
* Aviakit Vega
* Aviasouz Cruise
* Aviastroitel AC-5MP
* Aviate Raptor
* AVIC Lucky Bird
* Avid Flyer
* Aviomania Genesis Duo G2SA
* Aviomania Genesis Solo G1SA
* AV Leichtflugzeuge Vagabund
* BAaer Guri
* Bauer BAD-12 Gyrotrainer
* BDC Aero Puma
* Best Off Nynja
* Best Off Sky Ranger
* Bilsam Sky Cruiser
* ASAP Chinook Plus 2
* B&F Fk9
* B&F Fk12
* B&F Fk14 Polaris
* Bayraktar Tactical UAS
* Blackshape Prime
* Blue Yonder Merlin
* Blue Yonder Harvard
* Blue Yonder King Cobra
* Blue Yonder EZ Flyer
* Blue Yonder Twin Engine EZ Flyer
* BOT SC07 Speed Cruiser
* BRM Aero Bristell
* BRM Argos
* BRM Land Africa
* Bushcaddy R-80
* Bushcaddy R-120
* Buzzman L'il Buzzard
* Caldas 2G7 Vento
* Capella XLS
* Carlson Sparrow
* CBB O2
* Celier Kiss
* Celier Xenon 2
* Celier Xenon 4
* Celier XeWing
* CFM Air Dardo
* CFM Shadow
* Chernov Che-25
* Coavio DF 2000
* Colomban MC-100 Ban-Bi
* Colyaer Freedom S100
* Colyaer Gannet S100
* Colyaer Martin3 S100
* Cosmos Phase III
* Criquet Storch
* CSA PS-38 Tourer
* CZAW Parrot
* CZAW SportCruiser
* Dallach Sunwheel
* Dallair Aeronautica FR-100 Snap!
* DAR 21 Vector II
* Denney Kitfox
* Diamond DA20-A1 Katana
* Diamond HK36 Super Dimona
* Didier Pti'tAvion
* Direct Fly Alto
* Direct Fly ArGO
* Distar UFM-13 Lambada
* Dorna Parandeh Abi
* Dorna Free Bird
* Dova DV-1 Skylark
* Drachen Studio Kecur Royal 912
* DTA Combo
* DTA Evolution
* DTA Feeling
* DTA J-RO
* Dyn'Aéro MCR01
* Dyn'Aéro MCR4S
* Dyn'Aéro Twin-R
* Dynali H2S
* Dynali H3 EasyFlyer
* Eagle EA-100
* EDM Aerotec CoAX 2D/2R
* Egvoyager Voyager 203
* Ekolot JK-05L Junior
* Ekolot KR-030 Topaz
* ELA 07
* ELA 10 Eclipse
* ELA 09 Junior
* Elitar-202
* Elitar Sigma
* Etudes Andre Morin M85
* Euro-ALA Jet Fox
* Eurodisplay SR-01 Magic
* Euro Fly Flash Light
* Euro Fly FB5 Star Light
* Europa XS
* Evektor SportStar
* Evolution Revo
* Exkluziv Joker
* Falconar AMF-14H Maranda
* Fantasy Air Allegro
* FD-Composites ArrowCopter
* Fisher Dakota Hawk
* Flaeming Air FA 04 Peregrine
* Flight Design CT
* Flight Design MC
* Flight Team Twister
* Flying Legend Hawker Hurricane Replica
* Flying Machines FM250 Vampire
* Flying Machines FM301
* Flyitalia MD3 Rider
* Fly Synthesis Storch
* Fly Synthesis Syncro
* Fly Synthesis Texan
* FMP Qualt 201
* Freewind Bumble B
* Foxcon Terrier 200
* G1 Aviation G1
* General Aviation Design Bureau T-32 Maverick
* Gidroplan Che-22 Korvet
* Glasair GlaStar
* Gobosh 700S
* Gobosh 800XP
* Golden Avio F30
* Golden Circle Air T-Bird
* HB-Flugtechnik Amigo
* HB-Flugtechnik Cubby
* HB-Flugtechnik Dandy
* HB Flugtechnik HB-207 Alfa
* Horizontec Halcón H1
* Houde Bimax
* Humbert La Moto Du Ciel
* General Atomics MQ-1 Predator
* IAE VUT Marabou
* IAR-46
* Ibis GS-501 Urraco
* Ibis GS-600 Arrow
* Ibis GS-700 Magic
* Ibis GS-710 Magic
* Icarus F99 Rambo
* Icon A5
* ICP Amigo
* ICP Savannah
* ICP Vimana
* Ikarus C42
* Ikarus C52
* InterPlane Skyboy
* Ion Aircraft Ion
* Jihlavan Skyleader
* Jingmen A2C Ultra Seaplane
* Junkers Profly Ultima
* Just Escapade
* Just Highlander
* Just Superstol
* Kappa 77 KP 2U-SOVA
* Keitek Streamer
* Kohl Mythos
* Kolb Kolbra
* Kolb Mark III Xtra
* Kolb Slingshot
* Kubicek M-2 Scout
* Lamco Eurocub
* Laron Wizard
* LH-10 Ellipse
* Liberty XL2
* Light Wing AC4
* Lilienthal Bekas
* LISA Akoya
* Lockwood Aircam
* Lockwood Super Drifter
* Magni M-14 Scout
* Mainair Blade
* Marawing 1-L Malamut
* Medway Av8R
* Medway EclipseR
* Medway SLA100 Executive
* Microleve Corsario
* Millennium Master
* Moyes Dragonfly
* MSL Aero H80
* M-Squared Breese
* Murphy Renegade
* New Avio C205
* Nexaer LS1
* Niki Kallithea
* Norman Aviation J6 Karatoo
* Norman Aviation Nordic II
* Norman Aviation Nordic VI
* Norman Aviation Nordic 8 Mini Explorer
* North American Rotorwerks Pitbull II
* North Wing Sport X2
* Nova Coden
* OneAircraft One
* OSKBES MAI-208
* Pagotto Brako
* Pagotto Brakogyro
* P&M Explorer
* P&M PulsR
* P&M GT450
* Paradise P-1 LSA
* PC-Flight Pretty Flight
* Pegasus EDA 100 Flamingo
* Pegasus Quantum
* Pegasus Quik
* Pelegrin Tarragon
* Phantom II
* Phoenix Air Phoenix
* Piper Sport
* Pipistrel Alpha Trainer
* Pipistrel Sinus
* Pipistrel Virus
* Pro.Mecc Freccia Anemo
* Pro.Mecc Sparviero
* Progressive Aerodyne SeaRey
* Quicksilver GT500
* RagWing RW19 Stork
* RagWing RW22 Tiger Moth
* RagWing RW26 Special II
* Rainbow Aerotrike
* Rainbow Cheetah
* Ramphos Trident
* Rans S-6 Coyote II
* Rans S-7 Courier
* Rans S-10 Sakota
* Rans S-11 Pursuit
* Rans S-12 Airaile
* Rans S-16 Shekari
* Rans S-19 Venterra
* Rans S-20 Raven
* Rans S-21 Outbound
* Remos GX
* RMT Bateleur
* Roland Me 109 Replica
* Roland S-STOL
* Roland Z-602
* Roko Aero NG4
* Rokospol Via
* Rossi Shuttle Quik
* Rotorfly R-30
* Rutan SkiGull
* SAB C-100 Vulcan
* Shark.Aero Shark
* Scheibe Falke
* SkyCruiser Autogyro SkyCruiser
* Skyline SL-122 Pchelka
* Skyeton K-10 Swift
* Skyleader GP One
* SkyReach BushCat
* Skyrider Stingray
* Summit 2
* Sunward Aurora
* Sunward ST912
* Sunward STB912
* S-Wing Swing
* Skyleader 200
* Sea and Sky Cygnet
* Slepcev Storch
* Sling Aircraft Sling 2
* SlipStream Genesis
* Softeks V-24 Lastochka
* Solo Wings Aquilla
* Sport Copter Vortex
* Stellar Astra
* Storm 280
* Storm 300
* Storm 320E
* Storm RG Fury
* Swiss Excellence Risen
* Synairgie Jet Ranger
* Taiwan Dancer TD-3
* Tecnam Astore
* Tecnam P 92
* Tecnam P96 Golf
* Tecnam P2002
* Tecnam P2004
* Tecnam P2006T
* Tecnam P2008
* Tecnam Snap
* Terrafugia Transition
* Texas Aircraft Colt
* Titan T-51 Mustang
* Titan Tornado
* Titanium Explorer
* TL Ultralight TL-3000 Sirius
* TL-Ultralight Stream
* TMM Avia T-10 Avia-Tor
* Tomark Skyper
* Tomark Viper
* Triavio Italo
* Trike Icaros Adventure S
* Trixy Eye
* Trixy G 4-2 R
* Trixy Liberty
* Trixy Princess
* ULBI Wild Thing
* Ultra-Leicht Flugtechnik Speedy Mouse
* Ultravia Pelican
* Urban Air Samba
* US Light Aircraft Hornet
* Van's Aircraft RV-12
* Vervoost FV-3 Delphin
* ViS Sprint
* ViS ViS-3
* Weller UW-9 Sprint
* Whisper Aircraft Whisper
* World Aircraft Spirit
* World Aircraft Vision
* WLT Sparrow
* Zenith STOL CH 701
* Zenith STOL CH 750
* Zlin Savage Cub

## Specifications (Rotax 912 UL/A/F)
### General characteristics

* Type: four-cylinder, four-stroke liquid / air-cooled engine with opposed cylinders, dry sump forced lubrication with separate oil tank, automatic adjustment by hydraulic valve tappet, dual CD carburetors, mechanical diaphragm pump, electronic dual ignition, electric starter, integrated reduction gear 1 : 2.273 or 1 : 2.43
* Bore: 79.5 mm (3.13 in)
* Stroke: 61 mm (2.40 in)
* Displacement: 1,211.2 cm$^3$ (73.91 in$^3$)
* Length: 561 mm (22.1 in)
* Width: 576 mm (22.7 in)
* Dry weight: 60 kg (132.3 lb) with electric starter, carburetors, fuel pump, air filters and oil system

### Components

* Valvetrain: OHV, hydraulic lifters, pushrods, rocker arms
* Fuel type: Unleaded: 87 octane AKI (Canada/USA) / 90 octane RON (European) or higher. Leaded fuel and AVGAS 100 LL can be used but are not recommended.
* Oil system: Dry sump with trochoid pump, camshaft driven
* Cooling system: Liquid-cooled cylinder heads, air-cooled cylinders

### Performance

* Power output: 59.6 kW (79.9 hp) at 5,800 rpm
Power density: 48.71 kW/L
* Compression ratio: 9:1
* Fuel consumption: 15.0 liters/h at 5,000 rpm (75% power)
* Specific fuel consumption: 285 g/(kW·h) at 5,500 rpm (maximum continuous power)
Specific power: 0.98 kW/kg