Given the following information determine the greatest distance from an obstacle, at the failure of one engine would cause an MRJT1 aircraft to clear the obstacle by the statutory minimum during the drift-down, the fuel used during the drift-down, and time taken to reach the obstacle.
Cruise Pressure Altitude 34,000 ft.
Gross Weight at Engine Failure 54,000 kg.
Ambient Temperature ISA +15°C.
Wind Component 40 kt tailwind.
Engine and Wing Anti-icing System on.
Air Conditioning System on throughout the drift-down.
Obstacle Pressure Altitude 14,000 ft.
One engine inoperative.
1. Select the appropriate graph for the given cruise altitude. For 34000 ft this is figure 4.25, which covers altitude between 33000 ft and 35000 ft.
2. Calculate the height required to clear the obstacle during the descent. The statutory minimum clearance during drift down is 2000 ft, so the required attitude at the obstacle is 14,000 ft + 2,000 ft = 16,000 ft.
3. Using the data in the table at the top left corner of the page adjust the gross weight at engine failure to reflect the conditions of the anti-icing and the air conditioning system. For the stated condition of engine and wing anti-icing systems on and air conditioning system on, the corrections are 54,000 kg + 5,650 kg (for anti-icing)= 59,650 kg. Note that an adjustment is required for air conditioning only when it is switched off, so no adjustment is required in this question.
4. Using the graph at the top right cornet of the page adjust the corrected gross weight at engine failure to reflect the temperature deviation. To do this enter the left edge of the sub-graph at 59,650 kg, then move parallel to the sloping lines to a point vertically above ISA +15°C. From this point move horizontally to the right edge of the sub-graph and read off equivalent gross weight at engine failure on the right vertical axis 61,500 kg.
5. Enter the right edge of the main graph and interpolate between 60000 kg and 65000 kg to locate the 61500 kg point. From this point draw a curve to the left interpolating between the printed curved lines on the graph. In doing this take care to take account of the fact that the curved lines converge as they move to the left.
6. Enter the left edge of the graph at 16,000 ft and draw a horizontal line to the left to intercept the curve drawn in stage 5 above.
7. At the intersection point interpolate between the dotted curved lines to estimate the fuel used during the drift-down. In this question the fuel used is approximately 1000 kg.
8. From the same intersection point draw a line vertically down to the bottom of the gridded area and read off the time required to drift-down. In this question it is approximately 29 minutes.
9. Extend the vertical line down to the reference line in the lower gridded area. From this point draw a line parallel to the sloping lines. From the existing 40 kt tailwind condition marked at the left edge of the graph, draw a horizontal line to the right to intercept the sloping line drawn previously. From the point of intersection of these lines drop vertically down to the bottom of the graph and read of the ground distance of approximately 175 nm.
If you are happy with the one above please try this one (something very like it appeared in a recent EASA ATPL exam)
Given the following information determine the greatest distance from an obstacle, at the failure of one engine would cause an MRJT1 aircraft to clear the obstacle by the statutory minimum during the drift-down, the fuel used during the drift-down, and time taken to reach the obstacle.
Cruise Pressure Altitude 37,000 ft.
Gross Weight at Engine Failure 44,000 kg.
Ambient Temperature ISA -15°C.
Wind Component 30 kt headwind.
Engine Anti-icing System on.
Wing anti-icing off.
Air Conditioning System on throughout the drift-down.
Obstacle Pressure Altitude 23,000 ft.
One engine inoperative.
Answers:
Ground distance 122 nm.
Time = 24 minutes.
Fuel used = 700 kg.
Last edited by keith williams; 10th Jul 2013 at 12:32.