Embraer Phenom 300
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Flight Cancelled / Delayed; General Release Refused / Aircraft Not Accepted
Manuals; Aircraft; Company Policy; Human Factors
Moisture was discovered in the NAV lights of both wings. I wrote them up. Maintenance Control sent me some cleverly worded Manufacturer's Guidance Letters and support documentation with pretty pictures from the Manufacturer that the moisture was ok to dispatch with... But there's nothing saying this in the Aircraft Flight Manual (AFM). Maintenance Control asked me to write 'entered in error' on the write-ups and I respectfully refused; citing a letter from the ZZZ1 FSDO stating that if the information isn't in the AFM; it isn't approved. This practice must stop. Of course an Original Equipment Manufacturer (OEM) will defend their product for a customer to keep them flying. Water; gas and fuel in close proximity [to electrical power] is just not a good idea. Common sense. Manufacturer's Guidance Letters [cannot] be used unless they are; in fact; incorporated into an FAA approved AFM. There's no way the FAA FSDO in ZZZ1 should cower from this position. Enough is enough. Legal is legal...Or give us a letter stating that the Aircraft Manufacturer can make whatever crazy and outlandish claim they [want] with; [or] without FAA approval. This is totally unsatisfactory.
A Captain reports about the continuing practice by his Company Maintenance Control to have pilots accept an Aircraft Manufacturer's Guidance Letter as approval to operate their EMB-505 (Phenom 300) with moisture in the sealed NAV lights of both wings. Pilot notes that Guidance Letters have to be incorporated into their FAA approved Aircraft Flight Manual (AFM) prior to being used for aircraft release. Aircraft refused.