In some installations these additional cooling requirements, coupled with the need for tuned intake and exhaust systems, may create installation issues relating to engine mounting and cowling. Aircraft designers, builders, owners and operators must take these factors into consideration when determining the suitablity of the 912 ULS or 912 S for a particular application. Potential users of the 912 ULS or 912 S should consult the 912 ULS / 912 S Installation Manual for more detailed information.

With their larger displacements, stronger power pulses and increased torque output, 912 ULS & 912 S engines may create greater demands on engine mounting systems compared to the 81 HP 912 engines.  Engine mounts may have to be modified to achieve acceptable vibration levels particularly at lower RPM. Engine mounts may also have to be stiffened to limit engine movement during engine start - up and shut down.

Temperature limits:

With a higher power output, the ROTAX 912 ULS / 912 S engines develop additional waste heat that must be dissipated. Therefore it is imperative that all the relevant temperature limits as specified in the Installation Manual and Operator´s Manual be verified.

The following limits must be verified and monitored on any new installation of a ROTAX 912 ULS or ROTAX 912 S.

- cylinder head temperature
- cylinder wall temperature
- oil temperature
- oil pressure
- EGT,
- rpm
- fuel pressure, etc.

It is imperative to check the cylinder wall temperature as demonstrated in the relevant Installation manual. Do not exceed max allowable recommended 190°C temperature.

The recommended oil radiator for the 912 ULS is Rotax part # 886 029.

Exhaust system 912 ULS / S:

At the moment BOMBARDIER-ROTAX offers two exhaust systems for the ROTAX 912 ULS or 912 S.

Standard or stainless steel exhaust system kit (non-tuned)
as used on the ROTAX 912 UL / 912 A / 912 F:

When this standard exhaust system is utilized, the 912 ULS or 912 S maximum take off performance will be reduce by approx. 2.0 to 3.5 horsepower (1,5 to 2,5 kW).

Tuned stainless steel exhaused system
as used on the ROTAX 912 ULS / 912 S only:

The external dimensions of this exhaust system kit are similar to those found on the standard exhaust system kit (see above) however this kit incorporates a different muffler internal design.

Please note: The 912 S or 912 ULS engine equipped with the specially tuned muffler may produce more noise than the 912 UL 81 HP engine.
The outside dimensions of the 912 S / 912 ULS exhaust system are similar to but not indentical to the 912 UL 81 HP exhaust system. Changes in exhaust mounting may be required in some installations.

See Non - Certified Options & Accessories For Rotax 912 & 914 Engines price list for information on intake and exhaust systems for the 912 ULS engine. (PDF doucument)
See Certified Options & Accessories For Rotax 912 & 914 Engines price list for information on intake and exhaust systems for the 912 S engine. (PDF doucument)

Air intake box:

To be able to obtain the rated performance of the ROTAX 912 ULS / 912 S a special ROTAX air intake box must be used in conjunction with the tuned exhaust muffler system.

This air intake box with drip tray will be offered as an optional item.

All ROTAX 912 ULS / 912 S will be tested at the factory prior to shipment in this configuration.

Important Note: If an air intake box of a different design is used, or no air intake box is used at all, changes in carburetor settings may be required. In addition, correct carburetor settings must be confirmed by a CO measurement carried out on each cylinder using the same procedure as set out for the ROTAX 914. (see Rotax Service Instruction SI-07-1997)

Click Here for a line drawing of the Rotax tuned intake airbox for the 912 ULS

Propeller:

The inertia of the propeller is limited to max. 6000 kgcm² (2050 lb.in²). The inertia of the propeller must be in compliance with Rotax Service Information 11 UL 91.

Oil:

It is important that a high quality oil be used on the ROTAX 912 ULS / 912 S. Therefore it is mandatory that the manufacturer / operator complies with Rotax Service Information 18 UL 97, Rev. 1.

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