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The OEI Configuration is described on Page 62 of the S76 Performance and Operating Handbook and that configuration matches the performance found on the Page 22 graph There are specific conditions to achieve the performance shown on the graph on Page 22 - Single Engine, Maximum Continuous Power, Best Rate Of Climb Speed and Gear Up being the most important considerations Reminder - In the lower left corner of the graph you would be aware of the small BROC SPEED (Best Rate Of Climb - same as Vy) graph and from the course notes you will be aware of the simple short cut for working out TAS during a climb in the configuration used on this graph The rule is, regardless of the PA/IAS combination from the graph, when the IAS is converted to TAS with PA and OAT both being included on the flight computer, the TAS always works out to be around 74 kt under ISA conditions, 75 kt under ISA+10 conditions and 76 kt under ISA+20 conditions. TAS may reach 77 kt if you are ISA+20 and have a high PA so if you are very hot and high maybe bump it that extra knot But remember that if you need to determine the target IAS for a climb or to maintain height in this OEI configuration simply convert your altitude to a PA and read the IAS directly off the graph. For a target IAS the graph figure is not adjusted for temperature The TAS short cut rule only applies for climbs based on OEI ROC at MCP and Vy with Gear UP as per the conditions of Page 23 in the OEI Configuration The TAS short cut doesn't apply for climbs based on OEI ROC at 2 1/2 minute power from the Page 22 graph, as this graph is for an engine failure during initial takeoff and performance includes a configuration with Gear DOWN. For Page 22 climbs the IAS also comes directly off the graph and that configuration is not used for any extended climbs Remember also for any ground speed calculations needed for climb gradient questions you MUST use TAS and the WV to get the ground speed. IAS is never used to get ground speeds Final Reminder - The ATPL(H) Exam Information Book - Item 4.3.10.3 on Page 33 confirms that "For examination purposes, unless a question refers directly to the 'Airspeed Calibration' charts in the Handbook, it is to be assumed that IAS equals CAS". So we do IAS to TAS conversions without an IAS to CAS step Please Click Here to return to the login page |