(3)
For the third malfunction, it is important to understand that during the engine start sequence, TGT limiting is inoperative. Therefore, should the pilot experience an engine TGT rise above 850o C during an engine start sequence, an emergency engine shutdown must be completed, and starter motored until TGT is below 538o C.
CAUTION: If start is attempted with ENGINE IGNITION switch OFF, do not place switch ON. Complete EMER ENG SHUTDOWN procedure.
(4)
The fourth malfunction, engine starter drops out prior to 52% Ng. The Ng section of the engine needs the starter to assist until 52% Ng speed. If the starter drops out too soon a hot start may result, complete an emergency engine shutdown.
(5)
An engine starter staying engaged past 65% Ng is the fifth, and final malfunction discussed. If the engine starter caution light remains on above 65% Ng, the pilot will pull downward on the malfunctioning engine PCL actuating the abort switch. If this does not cause the starter to drop out, the start valve is stuck in the open position, and hot air will eventually damage the starter. The pilot must then remove the air source as required.
i.
Engine Start with other Air Sources-There are three additional air sources available for engine starting. The use of an external air source, for example an Auxiliary Ground Power Unit (AGPU) or another aircraft, is the same as an APU start except the air source is connected to the receptacle on the left side
of the aircraft. To use this air source, the AIR SOURCE HEAT/START switch must be in the "OFF" position.
(1)
Ground Source- The Auxiliary Ground Power Unit (AGPU) is one of the external air sources used for engine starting.
(2)
Buddy Start- The Buddy Start system (aircraft to aircraft) is another method of starting the engines. Procedures for this method are found in the TM1-1520-237-MTF.
(3)
Cross Bleed Starting- Another method of starting the engine is cross bleed starting. Cross bleed starting utilizes the bleed-air shutoff valve to direct air from the operating engine to the opposite engine during the start sequence.
Starting one engine from the other (cross bleed start) is the same as starting an engine using the APU as the air source, except the AIR SOURCE HEAT/START switch will be in the ENG position. Pressure from the running engine compressor is used to start the other engine. To accomplish this, the running engine should be at 90% Ng with the RPM R at 100%, and the ENG ANTI ICE ON advisory light off. The collective may have to be raised to increase the Ng to 90% as an 18% loss of the Maximum Torque Available (MTA) on the air source engine will be experienced during the start sequence.
In order to attempt a cross bleed start, the #1 Ng must be above 90%and the #1 ENG ANTI ICE ON advisories must not appear with the #1 Engine at fly with an RPM R of 100%. A cross bleed start in flight may decrease the maximum torque available from the running engine by as much as 18%. Therefore, the APU should be used for in flight starting of an engine.
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