All aircraft fitted with upward facing or side facing fuel filler openings.
This Continuing Airworthiness Notice (CAN) alerts operators of the possibility of water contamination of the aircraft fuel if fuel filler caps and the fuel filler neck area are not correctly maintained.
This CAN is prompted by a report of an engine failure shortly after take-off which was attributed to water in the fuel. A fuel cap seal had failed and allowed rain water to enter the aircraft wing tank. With the pre-flight inspection, the fuel drain sample was reported to be “clear and bright” indicating that it was possibly all water.
In another incident in the UK, the engine on a Piper PA-38-112 ‘Tomahawk’ aircraft failed during initial climb-out which was probably caused by water contamination of the fuel. The aircraft had been parked outside during heavy rain. Due to deterioration of the fuel cap locking mechanism rain water leaked into the fuel tank.
Many general aviation aircraft are parked outside for extended periods and water contamination of fuel can occur due to problems with the filler caps by design, production and maintenance.
The CAA recommends that operators and maintenance providers accomplish the manufacturer’s inspection requirements specified for fuel filler caps and the fuel filler neck area. These inspections are usually described in the scheduled maintenance requirements of the aircraft maintenance manual (AMM).
Similarly, pilots should take note of the relevant pre-flight inspections requirements for fuel filler caps which are usually described in detail in the aircraft flight manual (AFM) or the pilot operating handbook (POH).
If requirements for such inspections are not addressed in the AMM, AFM or POH, this CAN provides recommendations for the maintenance and pre-flight inspections of fuel filler caps and the fuel filler neck area.
Maintenance Inspection Requirements:
Note : If any defects are found which might compromise the fuel filler/cap sealing and locking function, rectify before further flight.
Pre-Flight Inspection Requirements:
Note : If any defects are found during a pre-flight inspection (regarding the fuel cap/filler condition or fuel contamination), consult an engineer and have the defect corrected before further flight.
