# US 10,502,235 B2 · Method for tight control of bolt holes in fan assembly

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- Number: US 10,502,235 B2
- Document ID: US10502235B2
- Status: Granted
- Kind: B2
- Application number: 14/466,672
- Filed: 2014-08-22
- Published: 2016-08-25
- Granted: 2019-12-10
- Earliest claimed: 2013-11-06
- Assignees: United Technologies Corporation
- Applicants: United Technologies Corporation
- Inventors: Thomas J. Robertson; Mark W. Costa
- Web page: https://patentgrep.com/patent/US10502235B2

## CPC

- F04D 29/644: {especially adapted for elastic fluid pumps}
- F01D 9/042: {fixing blades to stators (fixing stator-rings in the casing or to each other F01D25/246)}
- F01D 25/243: {Flange connections; Bolting arrangements (F01D25/265 takes precedence)}
- F01D 25/246: {Fastening of diaphragms or stator-rings}
- F04D 29/522: {especially adapted for elastic fluid pumps}
- F05D 2220/32: in gas turbines
- F05D 2230/23: by permanently joining parts together
- F05D 2230/30: with deposition of material
- F05D 2230/41: Hardening; Annealing
- F05D 2230/60: Assembly methods
- F05D 2260/31: Retaining bolts or nuts
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

In a fan case having an annular outer wall with a plurality of fan case bolt holes there through, bushings are inserted into the fan case bolt hole and are dimensioned to define an annular gap between the bolt hole inner surface and the bushing outer surface. An adhesive material disposed within each annular gap between the bushing and the corresponding fan case bolt hole, with the adhesive material forming a liquid shim separating the bushing outer surface from the bolt hole inner surface.

## Claims

### Claim 1

A fan case assembly for a gas turbine engine, comprising:
a fan case having an annular outer wall and an annular sleeve disposed on an outer surface of the annular outer wall, the annular outer wall and the annular sleeve having a plurality of fan case bolt holes extending therethrough, wherein each of the plurality of fan case bolt holes has a bolt hole inner surface having a bolt hole inner diameter;
a plurality of bushings each having a cylindrical body having a bushing inner surface defining a cylindrical bore having a bushing inner diameter and a bushing outer surface with a bushing outer diameter that is less than the bolt hole inner diameter, wherein the cylindrical body of each of the plurality of bushings is inserted into a corresponding one of the plurality of fan case bolt holes with an annular gap being defined between the bolt hole inner surface and the bushing outer surface, wherein each of the plurality of bushings has a top edge and comprises a flange extending radially outwardly from the cylindrical body at the top edge and having a flange outer diameter that is greater than the bolt hole inner diameter, wherein the flange of each of the plurality of bushings directly contacts an outer surface of the annular sleeve; and
an adhesive material disposed within the annular gap between each one of the plurality of bushings and the corresponding one of the plurality of fan case bolt holes, wherein the adhesive material forms a liquid shim separating the bushing outer surface from the bolt hole inner surface of the corresponding one of the plurality of fan case bolt holes.

### Claim 2 (depends on 1)

The fan case assembly according to claim 1, wherein the adhesive material comprises an epoxy paste adhesive.

### Claim 3 (depends on 1)

The fan case assembly according to claim 1, wherein the plurality of fan case bolt holes comprise:
a first row of fan case bolt holes parallel to and proximate an aft edge of the fan case; and
a second row of fan case bolt holes parallel to the aft edge of the fan case and positioned forward of the first row of fan case bolt holes relative to the aft edge of the fan case.

### Claim 4 (depends on 1)

The fan case assembly according to claim 1, comprising a plurality of structural guide vanes each having a plurality of guide vane bolt holes, wherein the guide vane bolt hole for each of the plurality of structural guide vanes are positioned to axially align with corresponding fan case bolt holes.

### Claim 5 (depends on 4)

The fan case assembly according to claim 4, wherein a guide vane bolt hole inner diameter for each of the plurality of guide vane bolt holes is approximately equal to the bushing inner diameter of the cylindrical body.

### Claim 6 (depends on 4)

The fan case assembly according to claim 4, comprising a plurality of fasteners, with each fastener being inserted through one of the plurality of guide vane bolt holes and the corresponding cylindrical bore of one of the plurality of bushings to secure the structural guide vane to the annular outer wall of the fan case.

### Claim 7 (depends on 4)

The fan case assembly according to claim 4, wherein each of the plurality of structural guide vanes comprises a guide vane base having the plurality of guide vane bolt holes extending therethrough.