Armstrong Siddeley Motors: Minutes of a meeting to review the Python position

Development position: 99 hours running have been carried out during the period, making a total of 11401 hours P.240: Is being rebuilt for 150-hour modification approval test with the following main alterations: 1 D.9531 increased capacity scavenge pump 2 D.9360/15 Turbine blades fitted 3 D.9360/16 Improved interstage turbine labyrinth 4 D.9441 Reclipped distributor pipes 5 Modification to satellite bearing A number of Python satellite gears have failed recently: P.117 190 hours. Slight track breakdown, Cages satisfactory P.240 168 hour. Cages and track completely broken up Replacement bearings 27 hours. 5 failed tracks, cages OK P.146 (ex Rotol) 4 bearings 47 hours. 1 bearing 123 hours.All tracks in trouble. cages OK P.134 Flight engine 132 hours. Total 86 hours flight. 1 track broken down, 1 broken cage P.127 Flight engine 109 hours. Total 80 hours flight.Tracks OK. 2 broken cages (a) Bearing tracks. All the track failures seem to start in one corner of the front track P.240 will be built as follows: (i) New satellite pin will be fitted which should eliminate the support under the corners of the race (ii) A mixed set of tracks will be used, 2 etched and 3 subsequently phosphated (iii) The bearing clearance will be increased (b) Cages. Following Mamba experience the engine will be fitted with new steel cage having a cadmium nickel bearing surface on its outer diameter P.103: Is undergoing stall recovery test with an effectively larger LPC which was in fact a new valve made by Ultra. This is not the system we were developing on the Double Mamba and this work will be stopped in favour of the Double Mamba scheme P.104: This engine has been carrying out visual tip clearance tests in conjunction with stator cooling from the end of the compressor P.146 Has completed a 25-hour test with 80 deg oil inlet temperature but the satellite bearing tracks were in trouble at the end of the test 2 Other matters arising on python engines: 1 Jet pipe temperature control. With reference to the recent meeting at MoS on the Wyvern, Mr Dakin was asked to raise the modification immediately covering jet pipe temperature control 2 Anti-icing 3 Alternative fuel 4 Fuel pump seizures 5 Reverse torque switch 6 Tropical trials at Khartoum 7 Engine troubles (a) Turbine feed manifold. The first redesigned manifold is being incorporated in P.104 for the next test (b) New tabwashers for layshaft bearing nuts (c) BTH starters (d) Igniters Turbine disc cracking (iii) Existing flight engines with single discs will be limited to 100 hours flight (e) Failure of rear propeller roller bearing ex P.263: The bearing was too badly damaged for any investigation work to be done and no action is being taken (f) Loose rear nut on rear airscrew shaft roller bearing ex P.174. The trouble seems to be due to tabwasher breaking up (g) New interstage turbine labyrinth (h) 2-stage propellers. Rotol are introducing a second stop in the propeller which would require an extra selenoid and selenoid wiring (j) Increased capacity scavenge pump (k) Python harness (l) Cracked inner blade ring ex P.240. The 1st row nozzle inner blade ring was cracked after the 150-hour test (m) Front thrust bearing cage failure P.130. This cage was found to have picked up but the bearing was not fitted with the latest correct nip 8 RTO memos: X.25/482/JAF Mr Slatter said that all modifications to the gas starter trolleys are in hand X.4/1019/JAF. Wide cut fuel