- Start air valve for that unit may be sticking . The remedy is to give a kick in the opposite direction . Now a different unit will recieve start air due to the change in the crank position
- The reverse control valve is jammed.
- The reversing servo motor of the fuel or start air distributer is jammed or gets stuck befor reaching a new end position due to insufficient oil pressure . Therefore the enfine turns on air but no fuel is released as the rotation direction safegaurd block it
- If the engine is running in one direction and reversed , propellor continues to turn in that direction. Therfore more air and fuel is required for starting against the propelllor force . If the engine still doesnt start , the propellor may tend to turn the engine in the orginal direction ie opposite to the given movement . Therefore the rotational direction safegaurd blocks the fuel
- Reversing interlock malfunctioning
- The coil of the solinoid valve for thr desired direction or rotation doesnot get voltage
- Control air signal for desired direction of rotation doesnot reach the engine . Loosen piping and check the air route or the defective valve.
- Proximity sensor faulty ( of air distributer or fuek pump servo motor)
Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole is lesser in size than the corresponding circular hole. More over it is prime concern to have a smoothed generous radius at the corners to eliminate stress concentration. Hence other geometrical shapes like rectangle and square are ruled out. To compensate for the loss of material in the shell due to opening, a doubler ring has to be provided around the opening. The thickness of the ring depends on the axis length along the dirrection in which the stresses are maximum and the thickness of the shell. It is important to align the minor axis along the length of the vessel, as the stress in this direction is maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t= thickness of the shell plating Circumferential stress: Pd/4t More over a considerable material and weight saving is achieved as minor is along the direction of maximum stress.