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WX Man
1st Apr 2004, 20:00
(Send Clowns, I presume there are gremlins in the email system. I tried emailing these to the address you gave me).

I just haven't got a :mad: :mad: :mad: :mad: :* :{ :uhoh: :mad: ing clue what this question is asking. Can someone decipher the gobbledeygook?

Refer to CAP697 MRJT fig 4.4

Given:

DOM - 35,000kg
Expected Load - 12,000kg
Contingency, approach and hold fuel - 2,500kg
Dep AD elevation - 500 ft
Alt AD elevation - 30 ft

(NB it does actually say "Departure AD elevation". I assume it means "Destination AD elevation")

Find (i) Final Reserve Fuel and (ii) Relevant elevation.

(A) 2360 - Alternate elevation
(A) 1180 - Destination elevation
(A) 1180 - Alternate elevation
(A) 2360 - Destination elevation

-----------------
And another one!

A flight has to be made with the SEP1
For the fuel calculation, allow 10lb fuel for start up and taxi, 3 mins and 1 gallon of additional fuel to allow for the climb, 10 mins and no fuel correction for the descent.
Planned flight time (overhead to overhead) is 3h12min
Reserve fuel is 30% of trip fuel
Power setting is 25HG/full throttle @ 2100RPM, 20C lean.
FL70 and OAT is 11C.

(A) 286lb
(B) 268lb
(C) 215kg
(D) 252kg

:mad: What did I get? 309lb! Must be doing something wrong... enlightenment would be most welcome!

OneIn60rule
1st Apr 2004, 21:36
Did you forget to interpolate between the FL levels as well as the temp difference?

Temp is +11 at 7000 feet. It should be -1, since it's not then it's a total difference of 12 degrees.

Using values for the

ISA 8000 and 6000 you find the GPH AT 7000' to be >10.65

ISA+20 at 8000 and 6000 the GPH AT 7000 is >10.35

Interpolation between the two figures gives you a GPH of 10.47 GPH
(10.65-10.35 = .30/20 = 0.015 0.015 x 12 degrees = 0.18 subract .18 from 10.65 and you get 10.47)

Using time to destination and Fflow I find that I need 33.5 Gallons.
33.5 x 6 is 201 and 30% of 201 is 60.3 that makes it 261.3 pounds.

Now I have to add the 6 pounds and the 10 pounds and that makes it 277.3.

The answer is between 286 and 268 and so I'd probably go for answer A.

I think there's a hitch to the question though.

Tinstaafl
1st Apr 2004, 22:17
Unless the JAR exam provides climb fuel, or expects you to use cruise rates, have you considered the fuel used in the climb? 500' dept AD elevation would then be a factor in your climb fuel.

WX Man
2nd Apr 2004, 08:12
My interpolation concurs with yours, 1/60... I got 11C and 63lb/h (so, call it 10.5GPH).

However my figures are: (in lb)
Start up & taxi = 10
Trip = 3.2 x 63 = 201.6
Climb = 3 mins @ 63lb/h = 3.2; + 1USG (=6.5lb) = 9.7
Reserve - 30% of trip = 0.3 x 201.6 = 60.5
Descent = 10 mins x 63 = 10.5

So total = 292.3lb.

This is closest to (A) 286lb... which is marked as the correct one. But my answer being that far off suggests that there is something amiss in my calculations.

Tinstaafl.... climb fuel is not provided. Neither is distance ADEP - ADES. Which is why I am lost! This feedback is from a school that's an anagram of "Oxdorf".

Send Clowns
2nd Apr 2004, 08:26
Ooops, sorry Wx Man. Could be my spam killer - gets a little over enthusiastic sometimes. Drop me a PM with your email address so I can tell it you are not evil.

The first you must be right that it should say destination. The question is easy if you cut out the excess information (typical of JAA exams) and RTFA - read the answers! The rules for final reserve fuel for MRJT - 30 minutes hold 1500 feet above destination or, if destination alternate required, above the alternate. This cuts the answers down to (A) or (C). Note you can't even calculate the figure for the destination, as you don't know the fuel load there without alternate fuel being given.

Find the weight overhead the alternate (whoever wrote this question, which I didn't so not sure where it is from, got the answer wrong - they included all the contingency and holding fuel. If this fuel is intact then final reserve does not become an issue, so I think this is incorrect) which I make to be around the 47,000 kg mark, with a bit for the approach. Look in the table, to a higher weight rather than interpolating, I get 2280 kg/hr. Whoever wrote the answers went up to 2360 kg/hr. Half an hour at that fuel flow is 1140, 1180 for the other figures, but even a quick glance at the table with the vaguest idea of weight should tell you that 2360 in half an hour is wrong. 737-400s use of the order 2.5 tonnes per hour (varying from about 2-3 tonnes) in most normal conditions. almost twice that rate is really suspect!

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For the second, 1-in-60 is correct give or take 2 degrees (ISA +10° - note exam questions are more liekly to give ISA deviation than OAT) so fuel flow is 63.025 lb/hr (PPH column of the table).

From this and the 3 hours 12 minutes of trip, adding a gallon I make the trip fuel 208 lb. Multiplying by 130% to include reserves I get 269 lb, adding in the taxi fuel I make that 279 lb total. Now the question is not very clear as to whether the 3 minute climb and ten minute descent have to be added to the 3 hours 12 minutes for fuel calculation, or whether 1 gallon is the whole fuel for the climb and both times included in the total.

This question does not strike me as being close to the exam style. Contains too many bits - the "total fuel" questions tend to be separate from the CAP 697 questions. It is not well worded either.

OneIn60rule
3rd Apr 2004, 19:57
seen this question in the Abacus question bank but I wouldn't worry about it. This question is pretty elusive and has probably been rewritten or taken out of the bank.