I am not very good at the more complicated formulae available in excel so I tend to get around this by using IF statements. In your example you could set up to the far right of where your data is a series of IF statements in as many columns as you required. The first IF statement could be =IF(A2=now(sum-28),E2,0). Assuming in cell A2 you had a date and this date was less than 28 days then it would return the value in cell E2 - assuming your flight hours of course were in cell E2. You would copy this formula all the way down the rows you are using and then sum it at the bottom to give the number of hours flown in the last 28 days. For 90 days, 150 days or whatever else you need just put them in the next column using the same sort of formula as above but replacing the 28 with 90 etc.
Another good practice is to do a checksum somewhere on your spreadsheet (which should add to zero) to make sure that the sums of all the IF statements add up to your total hours flown. You can also hide all of the columns containing the formulas if you don't want to see them and just have a nice summary area somewhere on your spreadsheet which has references to the totals.
Hopefully you can follow what I meant. I am sure there are easier ways to do it but like I say I find IF statements a lot easier to deal with and to review.