I am trying to work through some calculations for maximum endurance on the Echo (Yay)!
I have two questions that I am trying to work through (Ex 4.18, Q1 and Q3) and they appear to be inconsistent.
The difference appears to be how the contingency fuel is managed.
Question 1 outlines contingency fuel needs to be accounted as part of the search fuel requirements
Question 2 outlines contingency fuel is only accounted for the transfer to/from the search site.
Which is correct?
1)
Fuel at start up = 120gal, with 42 gal needed for transfer to/from search site.Search is conducted at 35% engine power (17.2gal/hr for both engines)(Fixed reserve and startup/taxi = 15+3gal)
What is the maximum time at the search area?
Given Answer:
120-(15 +3) reserves102gal= trip fuelTake of contingency (102/1.1)= 92.7galMinus transfer fuel (92.7-42)50.7gal for search50,7gal at 17.2gal/hr2.94hrs or 177minutes
2)
Fuel at start up = 100gal, with 53 gal needed for transfer to/from search site.Search is conducted at 35% engine power (17.2gal/hr for both engines)(Fixed reserve and startup/taxi = 15+3)
Given Answer:
(53gal x1.1) +15+3 = 76.3galFuel at startup = 100gal100-76.3=23.7gal23.7gal/17.21.37hrs of 82.7min
BUT
Using the methodology from Question 1100-(15 +3) reserves82= trip fuelTake of contingency (82/1.1)= 74.5GMinus transfer fuel (74.5-53)21.5G for search21.5G at 17.2G/hr1.25hrs or 75minutes
I have included the pictures and worked answers.
What am I missing?
Hi Maverick007,
Just confirm that you are comparing questions 1 and 3? If so, the difference is in the wording of question no 3 "plan to hold over your destination" No contingency fuel is required on holding fuel over your destination.
Cheers W
Contingency fuel is 10% of the Trip Fuel. Holding fuel is not considered to be Trip Fuel.
Also, if a question relates to a search for a missing boat, such a flight is not necessarily an air transport flight, so contingency fuel need not be carried. The examiner would have to tell you whether or not you are carrying paying passengers.
