As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT PILOT NOTICED A DROP IN HYD PRESS ON GAUGE NEAR ZERO, ALSO NOTICED BOTH HYD FAIL ANNUNCIATOR LIGHT ILLUMINATED. PILOT DECIDED TO RETURN, PILOT PERFORMED EMER CHECKLIST ITEM THAT INCLUDED MANUALLY EXTENDING LG. PILOT LANDED WITHOUT FURTHER INCIDENT. TROUBLESHOOTING REVEALED A PIN HOLE IN THE FLAP UP LINE IN LT WW. FABRICATED NEW LINE PN 27-81032-135. PERFORMED HYD SYS FUNCTIONAL CHECKS, ALL SYS CHECKS WERE NORMAL.