The Rotax 912 is a normally aspirated, air- and water-cooled, horizontally opposed four-cylinder,
four-stroke, gear reduction-drive engine commonly used on certified aircraft, light sport aircraft,
ultralight aircraft and unmanned aerial vehicles. Rotax produced its 50,000th 912-series engine
in 2014.
Development The original 80 hp 912 engine has a capacity
of 1,211 cc and a compression ratio of 9.1:1. The later 912S is enlarged to 1,352 cubic
centimetres and has a compression ratio of 10.4:1, yielding 100 hp. The 912 A and F
are used in certified aircraft, such as the Diamond DA20, which is quite popular in Europe.
The 100 hp versions are used in many light sport aircraft, such as the ICP Savannah,
the Flight Design CTSW, the Tecnam P2002 Sierra and the Titan T-51 Mustang. The 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. The engine differs from conventional aircraft
engines in that it has air-cooled cylinders with liquid-cooled heads and uses a 2.43:1
gearbox to reduce the engine's relative high 5,800 rpm shaft speed to a more conventional
2,400 rpm for the propeller. Lubrication is dry sump, and fuelling is via dual CV carburetors
or fully redundant electronic fuel injection. Early 912 series engines have a shorter time
between overhaul than traditional engines, but are more fuel efficient than similarly
sized engines, e.g., Continental O-200. Effective 14 December 2009, 912 engines have had their
recommended Time Between Overhauls 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
they are certified to run on automotive fuel, further reducing running costs, especially
in areas where leaded AVGAS is not readily available. The engines are popular in Europe
and in United States Light Sport Category aircraft due to high power-to-weight ratio,
low fuel costs and relatively quiet operation. On 8 March 2012 the company displayed its
912 iS variant, a 100 hp version with direct fuel injection and an electronic engine management
unit. The version weighs 63 kg, which is 6 kg more than the standard 912S. The non-certified
912 iS targets the Light Sport and Experimental 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 decreased fuel consumption.
Variants The engine is available in the following versions:
912 A# Certified to JAR 22, 80 hp
912 F# Certified to FAR 33, 80 hp
912 iS Uncertified, 100 hp with direct fuel injection
and an electronic engine management unit 912 iSc
Certified, 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.
912 S# Certified to FAR 33, 100 hp
912 UL# Uncertified, 80 hp
912 ULS# Uncertified, 100 hp
912 ULSFR# Uncertified French Authority specification.
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 speed 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. Limitations
The manufacturer acknowledges the design limitations of this engine, warning pilots:
"Never fly the aircraft equipped with this engine at locations, airspeeds, altitudes,
or other circumstances from which a successful no-power landing cannot be made, after sudden
engine stoppage. This engine is not suitable for acrobatics.
This engine shall not be used on rotorcrafts with an in-flight driven rotor. It should
be clearly understood that the choice, selection and use of this particular engine on any aircraft
is at the sole discretion and responsibility of the aircraft manufacturer, assem- bler
and owner/user. Due to the varying designs, equipment and
types of aircraft, BRP-Powertrain grants no warranty or representation on the suitability
of its engine’s use on any particular aircraft. Further, BRP-Powertrain grants no warranty
or representation of this engine’s suitability with any other part, components or system
which may be selected by the aircraft manufacturer, assembler or user for aircraft application.
Non-compliance can result in serious injuries or death!
Unless correctly equipped to provide enough electrical power for night VFR, the ROTAX
912 ULULSFR is restricted to DAY VFR only. Certain areas, altitudes and conditions present
greater risk than others. The engine may require humidity or dust/sand preventative equipment,
or additional maintenance may be required. You should be aware that any engine may seize
or stall at any time. This could lead to a crash landing and possible severe injury or
death. For this reason, we recommend strict compliance with the maintenance and operation
and any additional information which may be given to you by your dealer."
Applications
Specifications 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
Stroke: 61 mm Displacement: 1,211.2 cm3
Length: 561 mm Width: 576 mm
Dry weight: 60 kg 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 / 90 octane RON 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 at 5,800 rpm Specific power: 48.71 kW/L
Compression ratio: 9:1 Fuel consumption: 15.0 liters/h at 5,000 rpm
Specific fuel consumption: 285 g/(kW·h) at 5,500 rpm
Power-to-weight ratio: 980 W/kg See also
Comparable engines Arrow 1000
D-Motor LF26 Hirth 3701
Hirth F-30 HKS 700E
Jabiru 2200 KFM 112M
Pegasus PAL 95 Revmaster R-2300
Sauer S 2200 UL Sauer S 2100 ULT
Sauer S 2400 UL ULPower UL260i
Related lists List of aircraft engines
References
External links The official Rotax Aircraft Engines Website
FAA Type Certificate Data Sheet E00051EN 912 UL 80 hp Engine Datasheet
912 ULS 100 hp Engine Datasheet 914 UL 115 hp Turbocharged Engine Datasheet