This is an example addon for manipulating PIREPs. In this, it adds a field called "load" to the PIREP form, and then on submit, checks to see the entered load is withing the constraints of the aircraft selected, based on whether it is a passenger or cargo flight.
This also serves as an example of how a VA can add their own custom checks for PIREPs to ensure data is entered the way they want it to be.
Of course, this isn't a substitute for the admin checking the PIREP.
You'll have to add this to your pirep_new.tpl:
<input type="text" name="load" value="<?php echo $_POST['load'];?>" />
Then placed the contents of the attached zip file into your core/modules folder.
pirepchecks.zip