As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON ENGINE START CYCLE RT, NG CLIMBED NORMALLY TILL APPROX 14 PERCENT THEN DECLINED RAPIDLY. FURTHER INSPECTION REVEALED THE SPLINE DRIVE INSIDE THE DRIVE GEAR HAD STRIPPED OUT CAUSING THE STARTER/GENERATOR TO BECOME UNCOUPLED FROM THE GAS GENERATOR SECTION. THE BREAKER IMPELLER/DRIVE GEARS WERE REPLACED ALONG WITH THE GENERATOR.