SlimHeader

×
PPL Video Lectures (10 Jul 2020)

PPL Video Lectures covering Aerodynamics, General Knowledge, Performance, Meteorology And Navigation are now available through our website see front page for details.

× Welcome to the CPL Performance question and answer forum. Please feel free to post your questions but more importantly also suggest answers for your forum colleagues. Bob himself or one of the other tutors will get to your question as soon as we can.

Review Questions Set 2 - Q 15

  • Posts: 50
  • Thank you received: 0

Airspeed created the topic: Review Questions Set 2 - Q 15

The question asks -
Question No 15
An Echo aeroplane is being prepared for a ferry flight with full fuel and the pilot only on board.
The empty weight and moment index is 1990 kg and 490 respectively. Assume the pilot weighs 83 kg. Ballast is
available in the form of 10 kg bars. The minimum number of these bars that must be carried is closest to

(a) 2 bars in the rear compartment
(b) 2 bars in the nose compartment
(c) 5 bars in the rear compartment
(d) 5 bars in the nose compartment

The answer in the book has a fuel load of 264 in the mains. Can I ask where you got 264kg from? The mains takes 100Gal, which is 272Kg.

If you use 272, then you get about 70Kg as the max allowable cargo in the rear.

Books answer is -
Question No 15
Do a trial load sheet
Item Weight arm moment
Empty a/c 1990 490
Row 1 83 19
ZFW 2290 509
2073
This is OK for C of G, so add the full fuel load
ZFW 2073 509
Mains 264 1780 47.0
Aux 218 2800 61.0
Take-off 2555 [point A] 617
This is outside the forward limit. Add 100 kg to the rear
Take-off 2555 617
Rear +100 5000 +50
2655 [point B] 667
Join point A to point B to find the ballast to add.
50 kg of ballast is required. See forward limit problems
in the text.
#1

Please Log in or Create an account to join the conversation.

  • Posts: 100
  • Thank you received: 3

Bosi72 replied the topic: Review Questions Set 2 - Q 15

>Can I ask where you got 264kg from?
>The mains takes 100Gal, which is
>272Kg.

Taxi fuel.

#2
Attachments:

Please Log in or Create an account to join the conversation.

  • Posts: 50
  • Thank you received: 0

Airspeed replied the topic: Review Questions Set 2 - Q 15

Thanks. That makes sense. It's these types of mistakes that I'm probably making in the exam. We need balance at Takeoff as well as ZFW, which means taking out the taxi fuel if we add full mains.

I also wouldn't have added full Aux tanks if I were doing the exam, which again would have failed me on this question. I'm so used to doing examples in that require only using FOB in mains.

While I understand that an understanding of the concepts of balance should make one aware of these tiny, but consequential mistakes. It also annoys me that there are so many tripping points in this exam.

I know, I know, John H will probably say that I need more practice. but after practicing for over 6 weeks, this is starting to get tiring.

Just about everyone I spoke to at my flight school has failed this twice and said that if they had to do it again now, they probably would fail again.
#3

Please Log in or Create an account to join the conversation.

  • Posts: 50
  • Thank you received: 0

Airspeed replied the topic: Review Questions Set 2 - Q 15

A thing I find difficult is accurately finding points like 617 or 667 IU on the charts, or 2555kg and 2655kg.

even numbers are easy to find, but these odd ones, or ones that are so close to an even number are more difficult, especially when the examiner asks for unrealistic accuracy.
#4

Please Log in or Create an account to join the conversation.

  • Posts: 2252
  • Thank you received: 194

bobtait replied the topic: Review Questions Set 2 - Q 15

You had 100 gallons in the mains at start-up, but the taxi fuel would be missing at take-off (which is what matters). You should start-up and taxi on the mains, so take 8kg out of the mains.
Start up 272kg
Less taxi fuel 8kg
Fuel at take-off 272 - 8 = 264kg
#5

Please Log in or Create an account to join the conversation.

  • Posts: 50
  • Thank you received: 0

Airspeed replied the topic: Review Questions Set 2 - Q 15

bobtait wrote: You had 100 gallons in the mains at start-up, but the taxi fuel would be missing at take-off (which is what matters). You should start-up and taxi on the mains, so take 8kg out of the mains.
Start up 272kg
Less taxi fuel 8kg
Fuel at take-off 272 - 8 = 264kg


Thanks. I’m not gonna forget this one soon.
#6

Please Log in or Create an account to join the conversation.

  • John.Heddles
  • John.Heddles's Avatar
  • Offline
  • ATPL/consulting aero engineer
  • Posts: 663
  • Thank you received: 70

John.Heddles replied the topic: Review Questions Set 2 - Q 15

A thing I find difficult is accurately finding points like 617 or 667 IU on the charts, or 2555kg and 2655kg.

A useful trick is to use a rule with a small scale - eg mm - so that you can exploit the similar triangles thing to get a simple scale from which to read intervals. You can buy a suitable rule at any tech drawing supplies outlet. Best to look for is a transparent plastic unit, fairly thin in thickness and with a bevelled edge so you can look through the rule and align things nicely.

Sequence -

(a) locate the segment on the graph scale in which you have an interest

(b) skew the rule as you need so that convenient whole units on the rule are aligned on the bounding main scale lines of the graph but with a suitable number of mm rule markings between the bounding lines - typically 10 or whatever suits the graph scale.

(c) you then have a very nice scale on the rule aligned with the graph scale (but at an angle) so that you can just simply read off the rule scale whatever you need in the way of numbers on the graph scale.

A bit of practice and your problem is sorted out well and truly - easy peasy.

Engineering specialist in aircraft performance and weight control.
#7

Please Log in or Create an account to join the conversation.

  • Posts: 2252
  • Thank you received: 194

bobtait replied the topic: Review Questions Set 2 - Q 15

Trouble is some students have been told by the supervisor that a rule is not on the 'permitted materials' list and they are not allowed to bring one into the examination room!!
#8

Please Log in or Create an account to join the conversation.

  • Posts: 50
  • Thank you received: 0

Airspeed replied the topic: Review Questions Set 2 - Q 15

Thanks John. Thats kind of what I've been doing, but I think I'll try using a more accurate ruler.

Regarding what Bob said. Trouble is some students have been told by the supervisor that a rule is not on the 'permitted materials' list and they are not allowed to bring one into the examination room!!

I think CASA and ASPEQ need to sort this out. The Invigilator Registrar Handbook, on page 28, part 11.1.3 states that "Standard Allowable Material - For all subjects, Candidates are permitted to have writing implements; comprising of two normal pens, 2 pencils, a basic pencil sharpener, an eraser and a ruler. and CASA's web page about allowed material under part 61 says "Material always permitted - A pen, pencil and eraser, and a ruler in exams requiring plotting and graphical work, are part of the material provided by the Invigilator.. Invigilator handbook

How can CASA state in the invigilator handbook that these basic things are "Standard Allowable Material", and state in their part 61 allowed material, that they are "Material always permitted", then continue to say they are provided by the invigilator? Part 61 allowed material

Surely, if plastic nav rulers and other nav equipment are allowed, then the student should be able to bring their own plastic ruler and pencils too. It should be no big deal.
#9

Please Log in or Create an account to join the conversation.

  • John.Heddles
  • John.Heddles's Avatar
  • Offline
  • ATPL/consulting aero engineer
  • Posts: 663
  • Thank you received: 70

John.Heddles replied the topic: Review Questions Set 2 - Q 15

Trouble is some students have been told by the supervisor that a rule is not on the 'permitted materials' list and they are not allowed to bring one into the examination room!!

Then it would appear that candidates should request that such invigilators remit the question to the CASA examiner at the time as they are both wrong and exceeding their authority, it would appear. I asked a similar question of the examiner recently and he provided the following link for my information -

www.casa.gov.au/licences-and-certificati...terial-under-part-61

(I don't know about the rest of you good folk but I, for one, find the CASA website to be one of the most non-intuitive sources of look up information known to mankind !)

The link has this gem of relevance to the point in question -

Nav equipment
When permitted, the term 'Nav equipment' includes:

dividers
compass

protractor
ruler (or straight-edge)

non-electronic 'aviation wind triangle and circular slide rule' computer. eg Jeppesen Sanderson CR or other brands of similar type or a manual slide rule (if the candidate so prefers it).[/b][/i]

Perhaps candidates should take a printout for support in discussions with the invigilator. The sort of rule I suggested and, especially, a Douglas Protractor, are both essential exams tools, despite the invigilator's nonsense. The consideration of ruler or straight edge is a red herring. The rule which I suggested provides all of rule, ruler, and straightedge capabilities.

I think CASA and ASPEQ need to sort this out.

So it might seem. I will refer this thread to the examiner for his thoughts on the matter.

and CASA's web page about allowed material under part 61 says

.. and it also specifies "navigation equipment" so you appear to have no problem ?

See www.casa.gov.au/standard-page/cpl-exams where one finds

Airservices List
AIP Book
ERSA complete
CAAP 92-1(1) and 234-1(2.1)
Navigation equipment
A ‘Basic calculator’
No other references or material permitted


then continue to say they are provided by the invigilator?

You might have confused me here a little ? I read the words to say that

Permitted material required to be supplied by the candidate:

A candidate may use either the Airservices List, OR the Jeppesen List of permitted materials ONLY. All other combinations of materials are NOT permitted.[/b][/i]

I am a pretty relaxed chap but I think I would have a robust, but very polite, discussion with the invigilator and request that a phone call be made, there and then, to the examiner so that your position is on the record with CASA for any subsequent remarking requests ?

Engineering specialist in aircraft performance and weight control.
#10

Please Log in or Create an account to join the conversation.

Time to create page: 0.291 seconds