PREAMBLE: The invention lead to an ingenious development of a
special compact, light weight, simple, hassle free and easy to operate tool. The tool there by eliminated the high risk of work environment on a fully equipped Helicopter and achieved the desired bush replacement parameters.
FIELD OF INVENTION: This invention relates to design &
development of a special purpose tool, used for removal and insertion of a bush on engine fitting mounting assembly on Helicopter. The single tool is capable of performing, both removal of existing bush and insertion of a new bush at the same place with required fit & tolerance.
USE OF INVENTION: The tool so developed being smaller in size
is directly operated to the engine fitting mounting assembly, on the transmission engine deck area of the Helicopter. This operation is carried out on a fully equipped Helicopter, just below the engine where accessibility is very minimal & critical too. Another unique feature of the design is the ability of the tool to work in a non conventional way.
This concept may be adopted for various applications having similar requirements of assembly/dis-assembly and equipment portability. This too holds good for critical, expensive, high risk and precision positioning of the equipments on to any variant of the Helicopters.
The special purpose device is more reliable and can be used in any condition.
PRIOR ART: The engine fitting mounting assembly was already press
fitted with a bush and this is to be replaced with a new bush. This dual exercise needs a mechanical force for both actions (extract & insert). As the helicopter is fully equipped there is hardly any access or space for the operator to do the job. Moreover this exercise is to be carried out at the customer's base for the already delivered helicopters with old bushes.
Another challenge involved is, the tool to be operated horizontally rather than the conventional method of vertical direction of force application.

OBJECT OF INVENTION:
The modern Helicopter is equipped with a twin engine transmission system. The engine along with Integrated Dynamic System (IDS) is installed on the transmission deck. Further the engine is connected and aligned to the IDS. The engine unit is installed on forward and rear, engine mounting brackets fitting, through forward inboard / outboard bracket assemblies and rear mount assembly of the transmission deck area . (Re.f. Fig.- 1, 2)
The engine fitting mounting bracket assembly, is a quite critical part of the transmission engine deck. This assembly is fitted with one no. of flanged bush (press fit type) and one no. of liner bush (sliding fit) (Ref. Fig.-5).
Due to design up gradation the already existing bushes are to be replaced with new bushes. More over the engine fitting mounting bracket cannot be removed individually (permanently fixed) out of the helicopter.

Therefore this exercise is to be carried out on helicopter without removing the engine & other hydraulic pipelines and LRUs. Because it leads to a very critical process & a lot of man power involvement, to remove, disassemble and again assemble back the related equipments. More over this needs a group of specialized people to travel to the customer bases and do the exercise.
This subsequently urged for a special type of compact and easy to handle tool to be operated within a less accessible space.
STATEMENT OF INVENTION:
The invention is unique, compact, light weight, simple, user friendly and special type where both removal and insertion of the bush is answered by a single tool. Because of the space constraint the tool is so designed to operate in a single direction i.e. from outer side of Helicopter.
Another uniqueness of the tool lies with the small size that allows the operators to work in a limited space without a much disturbance or disassembly of the parts/equipments from the Helicopter. Thus a lot of man power, time, effort, movement and expenses are saved.
DETAILED DESCRIPTION OF THE INVENTION:
The invention narrates for design and development of a special purpose tool capable of extracting and inserting of the bushes fitted to the critically mounted engine brackets over transmission engine deck area (just below the engine) of the Helicopter (Ref. Fig.- 3 & 4)

The tool (Ref. fig. 6) consists of a strong and rigid U-shaped Holding bracket (1) along with a Cylindrical holder (4).The Cylindrical holder (4)
has both external and internal threads. Together these two provide a strong grip of the tool on the engine fitting mounting bracket. In addition, this also acts as a support and guide for the Threaded pin (2) during both extraction and insertion of the bush.
A Threaded pin (2) goes through the Bracket & Cylindrical holder (1 & 4). The Threaded pin (2) takes the bush internal diameter as a guide for removing operation. Also one Cup type attachment (3) is provided at the opposite end face of the bush to ensure additional guide.
The advantage of the Cup attachment (3) is to provide guide and pressure acting area on the bush during removal of the bush. The pressure for removal is created by a Knurled thumb nut (5) right after the Cup attachment (3).
In the same way the new bush is pressed with the help of Threaded pin (2) ' having provision to guide and press the bush on its collar area when rotational force is applied by the help of a Tommy bar (6).

Each tooling item is easy to assemble and dis-assemble type, giving a flexibility to operate smoothly at the point of action with minimum disturbances to the assembled equipments, hydraulic connections & LRUs.

CLAIMS: We claim that
I. This is one of its kind special purpose compact & portable tool to work on critically mounted bush insertion and removal operation carried on the Helicopter Transmission engine deck area.
2. The tool has got minimum elements for hassle free operation.
3. There are no permanent fixed joints or sections thereby making it easy to assemble and disassemble at any point of time.
4. The unique thread distribution ensures separately for individual task.
5. The device is sturdy and stable thus minimizing the errors.
6. The device ensures safe, easy and effortless operation on Helicopter transmission engine deck area.
7. This eliminates the need of tool individually, for extraction and insertion.
8. Compact and portability makes it safe, in space constraint areas of action.
9. Light weight (approximately 750gms), easy to store and carry.
10. Less manufacturing cost.
10.a. Thus the tool drastically reduced the amount of work, time, effort & - manpower required to dis-assemble & re-assemble the equipments, hydraulics and LRUs back.
10.b. The schematic of the device has a high potential to be adopted for
similar critical assembly operations to be performed in-situ on Helicopters.