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Introduction Of Concept Of Negative Tolerancing As Per Functional Dimensioning And Tolerancing (Fd & T) Principles On Main Under Carriage Fitting
Abstract: This invention describes the Main Under carriage fittings used in LCA-Tejas Aircraft. The Main Under Carriage Fitting were not assembled properly with its mating parts while positioning since the mating part (Interfacing region) was tolerance to wide tolerance range. This lead to build up thickness of 0.5 mm. reworking of Parts required due this. To avoid this, negative tolerance has been introduced on the interfacing region. Parts are being manufactured with Negative Tolerance & installing without doing any kind of rework during assembly built.
Notices, Deadlines & Correspondence
Patent Information
Applicants
HINDUSTAN AERONAUTICS LIMITED
Inventors
1. SHRI. R BALAJI
2. SHRI VOLETI SRINIVASA CHANDRASEKHAR
3. SHRI. R SRINIVASAN
Specification
DESCRIPTION
TECHNICAL FIELD
The invention describes a process for Main Under carriage fitting while positioning in to structural frames / mating bracket of LCA- Tejas Aircraft.
BACKGROUND OF INVENTION
The Main under carriage fittings are used to mount Main Landing gear Assembly (MLG) of LCA Aircraft. While positioning of the Main under carriage fitting during Structure built, it was not properly seating with its mating parts/ interfacing Parts such as Frames #25, Frame #26, Longeron & Shear wall etc., due to open tolerance. This was lead to build up of thickness around 0.5 mm on interfacing region. Main under carriage fitting are being reworked during Centre Fuselage Assembly Built time. To avoid such a rework the Concept of negative Tolerancing as per Functional Dimensioning & Tolerancing (FD & T) principles has been introduced.
SUMMARY OF INVENTION
The Main under carriage fittings are designed by considering the Negative Tolerance so that final fitment would be achieved without doing any kind of rework during Structural Build Stage of LCA Tejas A/c.
DRAWINGS
Fig.l Position of Mating Parts
Fig.2 Interference Zone
PROCESS DETAIL DESCRIPTION
1. The positional alignment of the Main Under carriage Fittings Assembly was ensured by locking of Standard feelers (5mm) on Jig ICY points.
2. The interfacing Parts such as Longeron, Shear wall, Frame # 25, Frame #26 faces are having wide tolerance.
3. This leads to build up of thickness of 0.5 mm on interfacing regions.
4. Due to above issue, the interfacing area of the Main under carriage fitting was required rework all the time since Bottom Longeron & Shear wall (#25-#26) has to be finalized initially as per CF Build Sequence.
5. The Tolerance value of Main Under carriage Fittings on Basic dimension has been revisited and changed from Bilateral to Unilateral on Negative side on the interfacing zone.
6. Main Under carriage Fittings parts are being manufactured with Negative Tolerance and installed without doing any kind of rework on LCA Tejas Aircraft.
CLAIMS
1. We Claim that the concept of Negative Tolerancing on Main under carriage fittings of LCA- Tejas Aircraft.
Documents
Application Documents
| # | Name | Date |
|---|---|---|
| 1 | 6824-CHE-2014 ABSTRACT 31-12-2014.pdf | 2014-12-31 |
| 1 | 6824-CHE-2014 FORM-5 31-12-2014.pdf | 2014-12-31 |
| 2 | 6824-CHE-2014 CLAIMS 31-12-2014.pdf | 2014-12-31 |
| 2 | 6824-CHE-2014 FORM-3 31-12-2014.pdf | 2014-12-31 |
| 3 | 6824-CHE-2014 CORRESPONDENCE OTHERS 31-12-2014.pdf | 2014-12-31 |
| 3 | 6824-CHE-2014 FORM-2 31-12-2014.pdf | 2014-12-31 |
| 4 | 6824-CHE-2014 DESCRIPTION (COMPLETE) 31-12-2014.pdf | 2014-12-31 |
| 4 | 6824-CHE-2014 FORM-1 31-12-2014.pdf | 2014-12-31 |
| 5 | 6824-CHE-2014 DRAWINGS 31-12-2014.pdf | 2014-12-31 |
| 6 | 6824-CHE-2014 DESCRIPTION (COMPLETE) 31-12-2014.pdf | 2014-12-31 |
| 6 | 6824-CHE-2014 FORM-1 31-12-2014.pdf | 2014-12-31 |
| 7 | 6824-CHE-2014 CORRESPONDENCE OTHERS 31-12-2014.pdf | 2014-12-31 |
| 7 | 6824-CHE-2014 FORM-2 31-12-2014.pdf | 2014-12-31 |
| 8 | 6824-CHE-2014 CLAIMS 31-12-2014.pdf | 2014-12-31 |
| 8 | 6824-CHE-2014 FORM-3 31-12-2014.pdf | 2014-12-31 |
| 9 | 6824-CHE-2014 ABSTRACT 31-12-2014.pdf | 2014-12-31 |
| 9 | 6824-CHE-2014 FORM-5 31-12-2014.pdf | 2014-12-31 |