FORM 2 THE PATENTS ACT, 1970
(39 of 1970) & The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Device to blank the Cut Out for Removal of Foreign Object from
Inaccessible Location
2. APPUCANT(S)
(a) NAME: HINDUSTAN AERONAUTICS LIMITED
(b) NATIONALITY: INDIAN
(c) ADDRESS: Dy. General Manager (Design-DA), AURDC, AIRCRAFT
DIVISION, Hindustan Aeronautics Limited (HAL) POST-HAL TOWNSHIP, TakNIPHAD, NASIK- 422207
3. PREAMBLE TO THE DESCRIPTION
COMPLETE The following specification
particularly describes the invention and
. the manner in which is to be performed.

4. DESCRIPTION (Description shall start from next stage.)
Refer Annexure I
5- CLAIMS (Not applicable for provisional specification. Claims should start with the preamble - "I/We claim" on separate page)
Refer Annexure II
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on separate page)
Refer Annexure III

[0001] Title of the Invention
Device to blank the Cut Out for Removal of Foreign Object from Inaccessible Location
[0002] Field of the Invention
The invention relates to a superior mechanical device used to blank or close the cut out made to remove Foreign Object (FO) from inaccessible places typically in aircraft sub-assemblies like wing, stabiliser, air intakes, air channel, vertical/ ventral fin etc.
[0003] Background of the Invention
Foreign Object Debris (FOD) refers to damage to an aircraft system or sub system attributed to Foreign Object (FO). FO is an alien to aircraft or system/ sub system which is not intended to be present at a particular location, which could potentially cause damage. Any damage attributed by a FO can be expressed in physical or economic terms and may degrade the products, and cause safety issues or deplete performance characteristics.
In many cases the FOD may cause damage, and/ or failure to product if the product is put in use. Typically, potential FOD examples in aircraft are:
√ Metal or wire clippings, electrical terminals, connectors, parts of
components etc. √ Tools, hardware, debris left in the vicinity due to human errors. √ Birds and other animals during exploitation and preservation of
aircraft. √ Construction debris (burrs, metal left overs etc.).

FO may be of one or more of the above articles entrapped in the areas not accessible after assembly of the aircraft, during manufacturing, exploitation or servicing of aircraft. Any area when exposed to foreign objects may potentially cause a system or product failure. In some of the areas, the construction of the aircraft assembly is such that once build/ assembled, it is difficult to access the internal compartments/ areas for removal of FO if any. In cases, when FO is observed in these closed compartments and cannot be removed. Removal of the FO in such cases require extensive dismantling of several structural components, which are integrated together by means of fasteners to form structural assemblies. This approach of FO removal is exhaustive time-consuming and labour intensive and thus costly and may result in threat to structural integrity of the assembly.
[0004] Brief Summary of the Invention
The present invention relates to a superior device designed to blank the cut out for removal of FO from inaccessible places in assemblies of aircraft, thus preventing potential damage to aircraft system and sub systems, reducing aircraft downtime and restoring aerodynamic contour/ surface.
The superior device (4) is an assembly consisting of fastener (6), circular locking device (12) and flanged spring (8). The fastener (6) is threaded shaft (22) with a planer surface (24) at one end and a head (19) at the other end. Circular locking device (12) has internal threads (13) with planar surface at one end and countersunk head at other end (27). Flanged spring (8) has taper flanges (29) & (30) and a circular hole (36) at center to accommodate fastener threaded shaft (22).
The fastener (6) is secured by the threaded (13) circular locking device (12) butting on countersunk head on external side, the head of the fastener resting on flanged spring (8) and the taper flanges (29) & (30) of

flange spring (8) butting on planar Surface ((35) of internal component (9). The device extends through one or more components.
The features', purposes and benefits of the superior device (4) that have been described can be used in different area of sub-assembly or different assembly. Further details of the superior device (4) are elaborated in the following description and drawings. [0005] Detail description of the drawings
The invention can be better understood by reading the detail description of the disclosed embodiment followed by the accompanied drawings, embodiment of the invention is described with an example and with reference to the accompanying drawings/ sketches in which: Figure 1: is the installation of FO removal superior device (4) in inaccessible sub-assembly
Figure 2: is exploded view of the superior device (4) Figure 3: is cross section B-B
Figure 4: is a fastener (6) with shaft (22) and snap head (19) Figure 5: is a circular locking device (12). Figure 6: is a flanged spring (8).
[0006] Detailed Description of the Invention
The present invention provides details of superior device (4) customised for blanking/ closing of cut out made for removal of FO from inaccessible location i.e. stabiliser (1) of the aircraft.
The following specification particularly describes the invention and the manner in which it is to be performed:
After identification of the exact location of the Foreign Object by
suitable method/ means, make a circular cut out ΦC on Top/ Bottom of
the stabiliser (1). Attachment area (5) of stabilizer with fuselage as shown in Fig.1. The top/ bottom skin, longitudinal spar/ ribs (3) and lateral webs (2) are the boundaries of inaccessible/ closed compartment. Make a

circular cut out of diameter ΦC (refer Fig. 2) with central axis (18) in
closed compartment i.e. stabiliser (1) of the aircraft for removing the FO (refer Fig.1).
Remove the FO through circular cut ΦC' out using suitable method and install superior device (4) (refer Fig.1, Detail TV) to blank/ close the cut out. Fastener (6) with threaded shaft length (22) and head (19) at one end secures circular locking device (12) along with flanged spring (8) forming a superior device (4) (refer Fig.3).
Fastener (6) (refer Fig.4) is in two parts where in the first part forms the head (19) at one end, extended through the second part with threaded
shaft with external threads (7) of diameter 'ΦD' through merging fillet (20).
It has a central axis (18A) and a slot (25) of width 'E' at other end of head for the engagement of tool for tightening of the fastener. At the flat end (24), chamfer (23) is provided for easy entry of shaft (22) into threaded circular locking device (12).
Circular locking device (12) (refer Fig.5) with internal threads (13) has central axis (18B) and slot (26) of width 'L' at countersunk head (27) for engagement of tool for tightening (refer Fig.5). One end of circular locking device has countersunk head (27) with angle (M°) of height 'F' with merging fillet (28) extended shaft with internal threads (13). The shaft has internal thread of diameter '42' and external diameter 'Φl' with a length 'G'.
Countersunk head (27) with planar surface flushes with external components/ skin (11) providing smooth external contour (34).
Flanged spring (8) (refer Fig.6) has central axis (18C) with a hole of diameter ΦS' at center and tapered flanges (29) & (30). The flanged
spring width (P) is less than diameter '<|>r and length (N) more than
diameter Φl The flanges are tapered with merging fillet (32) and width
(31) at bottom and height 'Q
The procedure for removal of FO and installation of the superior
device is described below. Drill a circular hole of diameter ΦC' through

and through the components (9), (10) and (11) and make countersunk with angle M° on stabiliser skin (11) (refer Fig.2). Insert the fastener (6) and flanged spring (8) through the circular cut out 'ΦC Match the central axis
(18A) and (18C) with central axis (18) as represented in the exploded view (refer Fig.2). Butt the surface (21) of the head (19) of fastener (6) to the surface (33) of the flanged spring (8) (refer Fig. 2).
Hold fastener (6) along with the flanged spring (8) and engage circular locking device (12) from the external side of skin (11) with external contour (34) matching the central axis (18B) with central axis (18) of hole
of diameter Φl Engage the tool in slot 'L' and tight the circular locking
device (12) with sufficient torque so as to butt tapered flanges (29) and (30) on component (9) planar surface (35) as represented in Fig.3.

Title: Device to blank the Cut Out for Removal of Foreign Object from Inaccessible Location
[0007] We claim:
1. The superior device (4) assembly intended for blanking or closing of
cut out ΦC' made for removal of Foreign Object (FO) from
inaccessible/ closed compartmentsof aircraft comprises of:
a fastener (6) with head (19) and threaded shaft (22) with external threads (7);
a circular locking device (12) with internal threads (13);
a flanged spring (8) with extended tapered flanges (29) and (30) and hole 'ΦS' 'at center;
wherein the external threads (7) of the fastener (6) and the internal threads (13) of the circular locking device (12) engage by rotating the circular locking device (12) along with
r
flanged spring (8) as a superior device assembly (4);
wherein the tapered flanges (29) and (30) of flanged spring (8) rests on the planar surface (35) of the inner most component (9);
wherein the head (19) and the flanged spring (8) are on the internal side of the closed compartment and the counter sunk head (27) of the circular locking device (12) flushes with the external contour (34) of the compartment;
2. The fastener (6) of claim 1, wherein the external diameter (ΦD' of the
threaded shaft (22) is equal to the internal diameter 'ΦH' of the circular locking device (12) ; the length 'G' is selected based on the grip thickness of components on which the cut out 'ΦC is made.

3. The circular locking device (12) of claim 1, wherein the external
diameter Φr of the circular locking device (12) is equal to the diameter
of cut out 'ΦC' in the closed compartment; the countersunk height 'F' is less than or equal to the thickness of external skin (11); the length (15) is based on the grip thickness 'G' on which the cut-out '<ΦC is made.
4. The flanged spring (8) as claimed in Claim 1, wherein the width (P' of
flanged spring (8) is less than the diameter (ΦC' of cut-out in the closed
compartment; the thickness of flanged spring (8) is sufficient to prevent bending or bulging during application of torque.
5. The device assembly (4) as claimed in Claim 1, wherein central
axis(18A) of fastener (6), central axis(18B) of circular locking device
(12) and central axis(18C) of flange spring( 8) are aligned about the
central axis (18) of the circular cut out 'C ; used for blank/ close
variable thickness 'G' and diameter of components '<|>C\ at cut out made, for removal of FO by varying the length (15) and (16) and diameter '<|)D' of fastener (6) & circular locking device (12) and length of flanged spring 'N'.
6. The method for securing superior device assembly (4) as claimed in
claim 1, involves the following steps:
Identify the location of foreign object and make a circular cut out 'ΦC' with central axis (18A);
Insert the fastener (6) and the flanged spring (8) through the circular cut out 'ΦC;
Insert the flanged spring (8) through the circular cut out ΦC insert the external threaded shaft (22) of the fastener (6) in the hole ΦS' of the flanged spring (8);

Align the central axis (18A) of fastener (6) along with the flanged spring (8) with the central axis (18B) of the cut out
ΦC';
Engage the threads (13) of the circular locking device (12) with the threads (7) of the fastener (6);
tighten the assembly by applying torque to the circular locking device (12) until the countersunk head (27) flushes with the external contour (34) of the closed compartment;
trim or file the threaded shaft (22) of the fastener (6) in flush with the external contour (34);
7. The method for securing superior device assembly(4) as claimed in claim 6:
reduces wastage of precious raw materials at least by 30-40%;
requires less labour hours at least by 30 - 40 %;
incurs less cost and reduces the downtime of the aircraft for removal of FO.