ROTAX
®
GmbH
d01634
SERVICE INSTRUCTION
AIRCRAFT ENGINES
INTRODUCTION OF A NEW ROCKER ARM BUSHING
FOR ROTAX
®
ENGINE TYPE 912/914 (SERIES)
SI-912-009
SI-914-010
Repeating symbols:
Please, pay attention to the following symbols throughout this document emphasizing particular information. WARNING:
Identifies an instruction, which if not followed, may cause serious injury or even death. CAUTION:
Denotes an instruction which if not followed, may severely damage the engine or could lead to
suspension of warranty. NOTE:
Information useful for better handling.
1) Planning information
1.1)
Engines affected
For all versions of the engine type:
- 912 A
from S/N 4,410.472 onward
- 912 F
from S/N 4,412.817 onward
- 912 S
from S/N 4,922.768 onward
- 912 UL
from S/N 4,404.621 onward
- 912 ULS
from S/N 4,427.487 onward
- 912 ULSFR
from S/N 4,429.709 onward
- 914 F
from S/N 4,420.314 onward
- 914 UL
from S/N 4,418.104 onward
1.2)
Concurrent ASB/SB/SI and SL
none
1.3)
Reason
Because of our ongoing commitment to product quality and innovation, we are proceeding with a change of the
rocker arm bearings from a sintered bronze bushing to a synthetic bushing.
1.4)
Subject
Introduction of a new rocker arm bushing for ROTAX
®
engine type 912/914 (Series).
This information is intended to assist the aircraft builder and operator in achieving the proper operating conditions,
correct engine installation and consequently optimum performance and reliability.
1.5)
Compliance
Optional at the time of overhaul or at necessary replacement of old style bushings.
1.6)
References
In addition to this technical information refer to current issue of
- Illustrated Parts Catalog (IPC)
- Maintenance Manual (MM)
1.7)
Interchangeability of parts
At replacement ensure that:
- Used rocker arms which are beyond the specified wear limit may be sent to an authorized overhaul facility for
necessary rework. Wear limits according to the relevant Maintenance Manual.
- For parts volume per engine see section 2.2. SI-912-009
SI-914-010
page 2 of 4
OCTOBER 2001
Initial issue
Copyright - ROTAX
®
GmbH
2) Material Information
2.1)
Material - cost and availability
Price and availability will be supplied on request by ROTAX
®
Authorized Distributors or their Service Center.
2.2)
Material requirement per engine
2.2.1)
Engines of the type
- 912 A
from S/N 3,792.551 to S/N 4,005.195
- 912 UL
from S/N 3,792.501 to S/N 4,005.195
a) parts requirement:
Fig.no.
New p/n
Qty/engine
Description
Old p/n
Application
-
854 340
NB
rocker arm left assy.
854 170/ 172
cylinder head
-
854 342
NB
rocker arm right assy.
854 175/ 177
cylinder head
-
933 397
NB*
rocker arm bushing
-
rocker arm
* 1 bushing per rocker arm required NOTE:
Parts volume is valid only for cylinder heads with pressed-in rocker arm shafts.
b) wear limits:
Designation
new
wear limit
mm
(in.)
mm
(in.)
rocker arm bore (with rocker arm bushing p/n 933 397)
rocker arm shaft bore
with synthetic bushing installed .............. 12,060÷ 12,090
(0,4748 ÷ 0,4760) ..... 12,10 (0,4764)
rocker arm shaft. .................................... 12,023÷ 12,034
(0,4733 ÷ 0,4738) ..... 11,95 (0,4705)
rocker arm bushing radial clearence ......... 0,026÷ 0,067
(0,0010 ÷ 0,0026) ....... 0,10 (0,0039)
2.2.2)
Engines of the type
- 912 A
from S/N 4,005.196
- 912 F
commencing with serial production
- 912 S
commencing with serial production
- 912 UL
from S/N 4,005.196
- 912 ULS
commencing with serial production
- 912 ULSFR
commencing with serial production
- 914 F
commencing with serial production
- 914 UL
commencing with serial production
a) parts requirement:
Fig.no.
New p/n
Qty/engine
Description
Old p/n
Application
1
854381
NB
rocker arm left assy.
854385
cylinder head
1
854391
NB
rocker arm right assy.
854395
cylinder head
1
933395
NB*
rocker arm bushing
-
rocker arm
* 1 bushing per rocker arm required
b) wear limits:
Designation
new
wear limit
mm
(in.)
mm
(in.)
rocker arm bore (with rocker arm bushing p/n 933 395)
rocker arm shaft bore
with synthetic bushing installed .............. 12,020÷ 12,050
(0,4732 ÷ 0,4744) ..... 12,10 (0,4764)
rocker arm shaft. .................................... 11,983÷ 11,994
(0,4717 ÷ 0,4722) ..... 11,95 (0,4705)
rocker arm bushing radial clearence ......... 0,026÷ 0,067
(0,0010 ÷ 0,0026) ....... 0,10 (0,0039) SI-912-009
SI-914-010
page 3 of 4
OCTOBER 2001
Initial issue
Copyright - ROTAX
®
GmbH
3) Accomplishment / Instructions
Accomplishment
All the measures must be taken and confirmed by the following persons or facilities:
- ROTAX
®
-Airworthiness representative
- ROTAX
®
-Distributors or their Service Centers
- Persons approved by the respective Aviation Authority
- Persons with type-specific training (applicable only for non-certified engines) WARNING:
Proceed with this work only in a non-smoking area and not close to sparks or open flames. Switch off
ignition and secure engine against unintentional operation. Secure aircraft against unauthorized
operation. Disconnect negative terminal of aircraft battery. WARNING:
Carry out work on a cold engine only. WARNING:
Should removal of a locking device (e.g. lock tabs, self-locking fasteners, etc.) be required when
undergoing disassembly/assembly, always replace with a new one. NOTE:
All work has to be performed in accordance with the current Maintenance Manual of the respective
engine type.
3.1)
General note
See fig. 1 and 2.
Be aware that the new rocker arm synthetic bushing (3) is fashioned as sliding fit in the rocker arm. The bushing
is also floating in the rocker arm bore after installation. Therefore the synthetic bushing is furnished with a
surrounding groove (1) to facilitate the oil supply.
The bushing is symmetrical and can be fitted therefore irrespective of position. For new wear limits and nominal
dimensions see section 2.2).
3.2)
Instructions
See fig. 1.
Apply oil on synthetic bushing accordingly, prior to fitting. CAUTION:
At installation of the rocker arm ensure that the bushing (3) is installed together with the rocker arm.
Furtheron it has to be assured that the correct rocker arm bushing is used for the relevant engine
type / engine serial number. See section 2 for identification and distinction of the rocker arm bushing
p/n 933 397 has 2 opposite bores (2).
- Restore aircraft to original operating configuration.
- Connect negative terminal of aircraft battery.
3.3)
Test run
Conduct test run including ignition check and leakage test in accordance with the current Maintenance Manual
of the respective engine type.
3.4)
Summary
These instructions (section 3) have to be conducted in accordance with compliance in section 1.5.
Approval of translation to best knowledge and judgement - in any case the original text in German language and the
metric units (SI-system) are authoritative. SI-912-009
SI-914-010
page 4 of 4
OCTOBER 2001
Initial issue
Copyright - ROTAX
®
GmbH
Fig. 1
005122
Fig. 2
005123
bushing pressed in
O
(1)groove for oil lubrication
(2)bore for oil lubrication
(3)bushing floating
4) Appendix
Following drawings should convey additional information:
rocker arm assembly, new version
rocker arm assembly, old version NOTE:
The illustrations in this document show the typical construction. They may not represent full detail or
the exact shape of the parts which have the same or similar function.
Exploded views are no technical drawings and are for reference only. For specific detail, refer to the
current documents of the respective engine type.
O: MOTORÖL (engine oil)