Hi Bob,
When we're doing an Echo question and it says that the seats have been removed, do we need make changes to anything else? Or subtract 5 from the total weight?

A few of the questions in the book have just ignored it.

Thanks!

I would need to see the question to answer in detail.

However the standard empty weight, presumably, includes seats. If this is the case, and the question doesn't indicate that the empty weight has already been corrected for the removal of one or more seats, then you will need to deduct the weight of each seat removed and adjust for the CG change (usually by a IU adjustment) to come up with a corrected empty weight and empty weight CG as the input to your loading calculations. Often this adjusted data will be referred to as a basic weight or similar term. Nothing laid down hard and fast anywhere.

This adjustment approach is very common in other than small aircraft where the configuration details may change marginally from flight to flight to accommodate different flight missions. It is quite usual just to make a correction to weight and IU by reference to a table of adjusted data for configuration changes.

As far as I know, the wording of questions like these usually states - "an Echo Aeroplane is loaded with all seats except the pilot's seat removed" then goes on to say that the empty weight is ..... You can safely assume that the figure given has been adjusted for the removal of the seats.

Engineers and designers are, of course, very fussy about the term 'Empty Weight'. Usually Basic Empty Weight is used in the flight manual to indicate that all such things as seats, unusable fuel, engine oil, hydraulic fluid and fixed ballast are included. If an adjustment to that configuration is made, CASA once used the term 'Aircraft Prepared for Service Weight' or 'Operating Weight' to indicated that the Basic Empty Weight has been adjusted.

Following on from Bob's comments (in my fussy engineer/designer manner) -

You can safely assume

If Bob has determined that from the examiner then, so be it and all is well. However, one is well advised, always, to read the detail of the question with appropriate care. I have known CASA (and antecedent organisation) theory examiners over the past 50-odd years and, if there is one thing they have refined as a fine art to a very high degree, it is the ability to pose questions in a manner which tests the candidates' ability to read and interpret detail.

For Australia, "empty weight" is defined - refer CAO 100.7.2 at www.legislation.gov.au/Details/F2018C00475. Likewise, "operating weight" gets a mention (in a vague sort of manner).

Basic empty weight is referred to in various documents, and is a very commonly used term. It is sort of similar to operating weight, generally, but must ALWAYS have a defined configuration summary to go with it - otherwise it becomes very much a "finger in the wind" sort of term. This is especially the case where the term is used in approved aircraft data. The WCO has no regulatory definition upon which to fall back without defining the term with the data.

The US folks use the term in a more disciplined manner. In general, the Australian weight and balance arena is expected to align progressively more with US practice so, in due course, things might become a little more logical. APS, in general, is used for heavy aircraft, especially in airline operations.