All Robinson R44 II aircraft fitted with a Lycoming IO-540 series engine.
This Continuing Airworthiness Notice (CAN) alerts operators of possible fuel leaks at the fuel control from fuel hose unions due to insufficient torque which could result in a catastrophic fire if leaking fuel comes into contact with a hot engine and exhaust components.
This CAN is prompted by a report of finding a significant fuel leak from the union of inlet fuel hose P/N B283-10 at the fuel control of a Lycoming IO-540 series engine fitted to a Robinson R44 II aircraft. The leaking fuel came into contact with parts of the hot engine and was discovered by the pilot after landing. The leak was attributed to the fuel inlet hose union being insufficiently torqued. The fuel inlet hose P/N B283-10 is connected to the Precision Airmotive fuel control P/N 2576630-4 at tee connector P/N 6600-04-04-04SS. The tee connector is covered by a heat wrap which must be removed to facilitate inspection of the hose unions.
Another R44 II aircraft was inspected during maintenance and the same inlet hose union was found to be insufficiently torqued.
Recommendation:
The CAA recommends that aircraft maintainers pay particular attention to the correct tightening procedures and torque value when tightening fuel hose unions. At the next scheduled maintenance inspection remove the heat wrap from the tee connector at the fuel control P/N 2576630-4 and check the tighten torque of the fuel fittings and unions of the fuel inlet hose P/N B283-10 and fuel return hose P/N B283-11.
AD action is not considered necessary at this time. Robinson Helicopter intends amending the R44 II maintenance instructions to specifically include an inspection of the fuel fittings at the fuel control unit.
All other enquires regarding this CAN should be made to:
Owen Olls
Airworthiness Specialist
Email: ollso@caa.govt.nz
Phone: 04 560 9569
