What was found
A FEW SECONDS AFTER TAKEOFF, WITH APU ON, WE GOT A STRONG METALLIC/ACRID ODOR. NO HAZE OR SMOKE NOTED. AT THE SAME TIME THERE WAS A LOUD HOWL/WHINING. CABIN TEMP STARTED TO INCREASE. SHUTDOWN THE APU & HOWLING/WHINING WAS NOTICEABLY REDUCED, BUT CONTINUED. IT CHANGED WITH POWER CHANGES. VERIFIED ACM COOLING TURBINE SIEZED. REMOVED FAULTY ACM COOLING TURBINE & INSTALLED AN OVERHAULED UNIT. REMOVED A DAMAGED ENVIRONMENTAL DUCT & REPLACED WITH NEW. REMOVED WATER SOCK, CLEANED & INSPECTED. FOUND SATISFACTORY. REINSTALLED WATER SOCK. OPS TEST OF ECU SYS FOUND SATISFACTORY, NO LEAKS NOTED. REFERENCE SIL GP-20 REV:2 CMM, AMM 21-51-00 & 12-19-02.