this question is based on circular motion in a vertical plane:
The maximum value of acceleration that the human body can safely tolerate for short time intervals is nine times that due to gravity. Calculate the maximum speed with which a pilot could safely pull out of a circular dive of radius 4.00m . The answer: 88.5m/s

I think the value of the radius of the circle is wrong - please check. A 4-meter radius flying circle is ridiculously small. Plus the answer you gave doesn't work with R=4m.

Here's how to solve this problem: at the bottom of the loop the pilot experinces the centripetal acceleration equal to v^2/R plus the regular force of gravity acting on his body of 1 g. The total of these must add to 9 g's. So:

v^2/R + g = 9g

Solve for v. I think you'll find that to get v=88.5 m/s the value for R is 100m, not 4m.