As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE: CS2. (AIR TURN BACK) STRONG SMELL AND SKYDROL FUMES INSIDE COCKPIT DURING TEST FLIGHT. FOUND SKYDROL RESIDUES ON AIR CYCLE MACHINE DUCTS, WATER SEPARATOR SOCK DUE TO LEAK DURING MAINTENANCE CHECK. CLEANED DUCTS AND REPLACED SOCKS PER MM 21-55-01.