Numbers on a helipad

[navigator72]

I took some aerial photos of a hospital helipad the other day and noticed there are 2 numbers in boxes painted on the ad. The numbers were 22 and 54, does anybody know what these mean?

 

[TundraT]

Ac 150/5390-2b

Weight Limitation. Any limitation on allowable weight should be placed in the center of the circle as viewed from the preferred direction of approach. Weight limitations should be stated in units of 1,000 pounds. A 9 indicates a weight-carrying capability of up to 9,000 pounds.

http://www.faa.gov/airports_airtraffic/airports/resources/advisory_circulars/media/150-5390-2B/150_5390_2b.pdf

 

[CMRJetDriver]

If the numbers were painted like this:

22
54

The top number indicates the weight limit of the helipad. The bottom number indicates the length of the sides in feet. Gotta keep those rotorblades out of the trees, buildings etc. Also, if the helipad is elevated (like offshore on a oil platform) you could land on a 20 foot pad, but if your rotorblades are 40 feet, you might be hoving out of ground effect, which is a performance consideration.