# US 9,752,593 B2 · Method of manufacturing a gas turbine engine having a fan track liner with an abradable layer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,593 B2 - Document ID: US9752593B2 - Status: Granted - Kind: B2 - Application number: 14/642,149 - Filed: 2015-03-09 - Published: 2016-06-23 - Granted: 2017-09-05 - Earliest claimed: 2014-03-31 - Assignees: ROLLS-ROYCE plc - Applicants: Rolls-Royce PLC - Inventors: Adam M Bagnall - Web page: https://patentgrep.com/patent/US9752593B2 ## CPC - F04D 29/526: {Details of the casing section radially opposing blade tips (ducts F04D29/545)} - B24B 19/14: for grinding turbine blades, propeller blades or the like (using grinding belts B24B21/16) - F01D 11/122: {with erodable or abradable material (blades having cutting or grinding tips F01D5/20)} - F04D 29/083: {especially adapted for elastic fluid pumps} - F04D 29/325: {for axial flow fans (blade mountings F04D29/34, blades F04D29/38)} - F04D 29/38: Blades {(for axial flow compressors F04D29/324)} - F01D 21/045: {special arrangements in stators or in rotors dealing with breaking-off of part of rotor} - F05D 2220/36: specially adapted for the fan of turbofan engines - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS - 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 ## Abstract A fan casing for fitment around an array of radially extending fan blades of a gas turbine engine. The fan casing includes an annular casing element; and an annular fan track liner positioned radially inward of the annular casing element. The fan track liner includes an abradable layer and an abrasive layer, the abrasive layer being positioned radially inward of the abradable layer and proximal, in use, to the fan blades. ## Claims ### Claim 1 A method of manufacturing a gas turbine engine, the method comprising: providing a series of fan blades about a hub, arranging an annular fan casing having an annular fan track liner circumferentially around the fan blades, wherein the fan track liner comprises an abradable layer and an abrasive layer on a radially inner surface of the abradable layer; and rotating the fan blades such that the abrasive layer removes a section from a tip of one or more of the fan blades, wherein the abrasive layer is substantially removed during rotation of the fan blades, and wherein the abrasive layer comprises abrasive particles. ### Claim 2 (depends on 1) The method according to claim 1, wherein the length of the one or more fan blades is reduced before the engine is mounted on-wing of an aircraft. ### Claim 3 (depends on 1) The method according to claim 1, wherein the abrasive layer is arranged so as to be substantially removed after engine pass-off and/or after running the engine at maximum speed for a predetermined number of rotation. ### Claim 4 (depends on 1) The method according to claim 1, wherein the abrasive layer comprises a resin matrix in which the abrasive particles are suspended. ### Claim 5 (depends on 1) The method according to claim 1, wherein the abrasive particles are sharp edged rhomboid particles. ### Claim 6 (depends on 5) The method according to claim 5, wherein the abrasive particles are diamond grit. ### Claim 7 A method of trueing blades of a gas turbine engine, the gas turbine engine comprising an array of blades arranged around a hub and a casing member positioned circumferentially around the blades, the casing member having an abradable layer, the method comprising: providing an arrangement for interacting with the fan blades to adjust the length of the fan blades during initial running of the engine; running the engine for a pre-determined time so that the arrangement interacts with one or more of the fan blades and adjusts the length thereof, wherein the arrangement is substantially removed during rotation of the fan blades; and providing an abrasive layer on a radially inward surface of the casing member and running the engine so as to abrade one or more of the blades and shorten the length thereof, wherein the abrasive layer comprises abrasive particles. ### Claim 8 A fan casing for fitment around an array of radially extending fan blades of a gas turbine engine, the fan casing comprising: an annular casing element; and an annular fan track liner positioned radially inward of the annular casing element, wherein the fan track liner comprises an abradable layer and an abrasive layer, the abrasive layer being positioned radially inward of the abradable layer and proximal, in use, to the fan blades, wherein the abrasive layer is a sacrificial abrasive layer, wherein the abrasive layer is arranged so as to be substantially removed after engine pass-off and/or after running the engine at maximum speed for a predetermined number of rotation, and wherein the abrasive layer comprises abrasive particles. ### Claim 9 (depends on 8) The fan casing according to claim 8, wherein the abrasive layer comprises a resin matrix in which the abrasive particles are suspended. ### Claim 10 (depends on 8) The fan casing according to claim 8, wherein the abrasive particles are sharp edged rhomboid particles. ### Claim 11 (depends on 10) The fan casing according to claim 10, wherein the abrasive particles are diamond grit.