According to the 2010 version of the FAI/CIVL Sporting Code for
hang gliding competitions, found here:
http://www.fai.org/hang_gliding/documents:

12. 6.3 Helmets

All pilots competing in 1st Category events must wear a helmet certified to
EN966 (HPG) at all times whilst flying.

My sources from the CIVL Plenary tell me that "any modification"
to an EN966 certified helmet decertifies it. This includes hacking off bits as
well as "installing headsets."

The Sporting Code states:

2. 17.11 Radio

Where national law permits, it is mandatory for pilots to carry a radio receiver
compatible with the organiser’s published frequency for safety communications.
This must be switched on in flight and set to either the competition frequency
or that of his team leader.

First, most, if not all of pilots' helmets have been "modified" to
install headsets which are basically needed to comply with the requirement for
the use of a radio. In addition, many EN966 helmets (some purchased at the
pre-Worlds) have been modified (hacked) for greater comfort and ease of use. Do
mean to tell me that the Worlds organizer is going to be forced to require that
pilots repurchase Icaro helmets at the Worlds?

Is this issue ripe for a pilot protest? All one pilot has to do to disqualify
almost all of the rest of the field is protest that his competitors are flying
with decertified helmets (how is the meet organizer going to know that a helmet
is not in certified condition?). He just buys a brand new Icaro helmet at the Worlds and keeps
it under a "certified" chain of custody for the first day's
flight, then protests everyone else. Easy to become the new World Champion.