Field of the Invention
The invention relates to Military Aviation Industry more'particular to achieve
precision angular tolerance for the multiple link bracket assemblies to
achieve acceptable throttle movement between front and rear cockpit of
engine control system mechanism of trainer (Tandem seat) aircraft
2 Background of the Invention
Trainer aircraft will have two cockpits and it- consists of several control
systems. One of the important control system in cockpit is engine control
system. It will be operated by pilot and co-pilot simultaneously through the
throttle control lever to control the fuel flow to the engine and it is linked
between front cockpit and rear cockpit.
Engine control system mechanism connected between front and rear
cockpit with connecting rods and four link bracket assemblies to obtain
required design throttle movement simultaneously.
Each of these link bracket assemblies have two lever assemblies, which are
assembled on link bracket shaft to maintain a design angular dimension with
in the +/- 5’ (minutes) tolerance, which is considered as critical tolerance in
engineering field. Once lever assemblies are installed on aircraft the rear
cockpit throttle lever should synchronized with front \cockpit‘throttle lever.
3 Brief Summary of the Invention
In order to achieve precision angular tolerance of +/- 5’ (Minute) of four link
bracket assemblies, a dedicated jig is designed and fabricated for multiple
link bracket assemblies with removable locators. This facilitates proper
clamping/holding by arresting the degrees of freedom while drilling and‘
reaming of locating holes at link bracket shaft along with lever assemblies
on a single platform.
4 Detail Description of the Drawings
Figure 1 shows Aircraft (11) and Engine Control System Assembly (12). It
consists of five connecting rod assemblies (1), eight lever assemblies (2),
four link bracket shafts (5), Front throttle quadrant assembly (3) and Rear
throttle quadrant assembly (4).
Figure 2 shows atypical link bracket assembly, it indicates link bracket shaft
(5) with two lever assemblies (2).
Figure 3 shows Schematic Diagram of Drill Jig with Link bracket assembly
(1), It indicates fixed base block1 (6) to arrest the degree of freedom in the
direction X & Y axis of the two lever assemblies (2) and link bracket shaft
(5) and will be locked to the fixed base block1(6) with removable locator
pins(8).
Figure 4 shows Schematic Diagram of Drill Jig with Link bracket assembly
2, It indicates fixed base block2 (7) to arrest the degree of freedom in the
direction of X & Y axis of the two lever assemblies (2) and link bracket shaft
(5) and will be locked to the block2 (7) with removable locator pins(8).
Figure 5 shows Schematic Diagram of Drill Jig with Link bracket assembly
3, It indicates fixed base block3 (9) to arrest the degree of freedom in the
direction of X & Y axis of the two lever assemblies (2) and link bracket shaft
(5) and will be locked to the block3(9) with-removable locator pins(8).
Figure 6 shows Schematic Diagram of Drill Jig with Link bracket assembly
4, It indicates fixed base block4 (10) to arrest the degree of freedom in the
direction of X & Y axis of the two lever assemblies (2) and link bracket shaft
(5) and will be locked to the block4 (10) with removable locator pins(8).
In aircraft industries, achieving precision angular tolerance limits between
the lever assemblies is difficult due to cumulative stack up tolerance errors.
Hence, it necessitates a special drill jig set up to achieve precision angular tolerance limits between the lever assemblies and to obtain required throttle
movement of an engine control system.
5 Detail Description of the Invention
A Drill Jig for drill and reaming mounting holes in link bracket shaft (5) along
with lever assemblies (2) designed and fabricated. This invention
overcomes the present difficulties as per the detail is below:
8 Numbers of removable locators pins (8) at each link bracket assembly are
made up of with steel Alloy material used to arrest lever assembly
movement in X and Y direction by using nuts made up of Steel material with
accuracy of 0.03 mm during drilling and reaming of mounting .holes in link
bracket shaft (5) along with lever assemblies (2) for engine control system
link bracket assemblies.
4 Numbers of fixed base blocks i.e. fixed base block1 (6), fixed base block2
(7), fixed base block3(9) and fixed base block4(10), are made up of
Aluminium Alloy material used to arrest movement in X and Y direction of
link bracket shaft(5) along with lever assemblies(2) of engine control system
and will be locking with removable locators pins(8) to the fixed base block
and drilling and reaming will be carried out with accuracy of 0.015 mm.
By using above jig setup, position of link bracket shaft (5) and lever
assemblies(2) are ensured by arresting movement in X and Y direction
before taking up' of drilling and reaming. operation as per the drawing
requirements using removable locator pin(8) arrangements.
Drilling of holes of 6 (H7) diameter on link bracket shaft(5) along with lever
assemblies(2) is carried out in stages using special drill guns, drill bits,
reamers with special guide bushes at 8 places individually.
By using above novel process setup, precision angular tolerance (+/- 5‘)
minutes on the link bracket assemblies is obtained along with required
throttle movement of an engine control system between the front and rear
cockpit
We Claim,
1. A process for achieving precision angular tolerance of Engine link
bracket assemblies comprising:
4 Numbers of fixed base block1 (6), fixed base blockZ (7), fixed base
block3 (9) and fixed base block4(10) and 8 Numbers of removable
locators pins (8);.
Wherein position of link bracket shaft (5) and lever assemblies(2) are
ensured by arresting movement it and Y direction before taking up
of drilling and reaming operation as per the drawing requirements
using removable locator pin(8) arrangements; and
Drilling of holes of 6 (H7) diameter on link bracket shaft(5) along with
15 lever assemblies(2) is carried out in stages using special drill guns, drill
bits, reamers with special guide bushes at 8 places individually.