Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Company Policy; Environment - Non Weather Related; Human Factors; Aircraft; Logbook Entry
We were assigned for a flight out of ZZZ. I noticed that five separate Navigation lights and strobes were filled with quite a bit of condensation.  I wrote the items up as Aircraft on Ground (AOG) grounding items as there is no MEL or Non-Essential Equipment and Furnishings (NEF) or Maintenance Control Order (MCO) allowance for such a condition: electricity in close proximity to water in a sealed area.  In fact; in other fleets operated here at our Air Carrier and at other companies; this condition is NOT allowed at all. Maintenance was quick to arrive that evening and signed off all five lighting AOGs.  The following day; the moisture was present in all five Navigation and Strobe locations.  I wrote up all five once again... AOG. The mechanic arrived shortly thereafter and worked with Maintenance Control and [company] to develop authorization under a Manufacturer's Guidance Letter to operate with water near LED lights and associated power sources in the NAV light and strobe light positions.  Seeing as the Manufacturer and the company did not advise the local FSDO or other branch of the FAA to get authorization for this Guidance Letter; I thought it prudent to file this report to get FAA oversight on the issue.  [Recommend] stop these off the cuff Guidance Letters that abrogate the safety process.  FAA involvement and authorization is a MUST!!!!
The reporter stated the affected lights with water condensation also include the aircraft Beacon and Emergency lights. All the Navigation; Strobes; Beacons and Emergency lights are sealed compartments without any drain holes or vacuum tubes to draw moisture out. The Navigation lights are a structural part of the [aircrafts] leading edge. How physically close to the fuel tanks these sealed lights are that could short with the amount of water condensation inside; is unclear. The reporter stated the Manufacturer's Guidance Letters are not legal for use as a Release document unless the letters are incorporated into their Aircraft Flight Manual (AFM); which means the FAA had approved the guidance letter(s). Maintenance Control has been using the manufacturer's guidance letters to dispatch aircraft even though the letter from the manufacturer allowing moisture/water in an electrical environment has not been incorporated into their AFM. He does not know the cause of the water ingress into the sealed compartments. Pilots are faced with enormous pressures to accept the aircraft with the unapproved guidance letters. He has filed previous reports on the same issue. He is hoping the FAA will get involved and consider this issue as a safety of flight concern.
During preflight my Captain noticed condensation on five separate Navigation lights; he told me and proceeded with the write up of the aircraft as Aircraft On Ground (AOG) since no MEL; Non-Essential Equipment and Furnishings (NEF) or Maintenance Control Order (MCO) allowance for that condition (electricity in close proximity to water in a sealed area).Next day; we arrived to preflight the Aircraft and the moisture was still present in all five Navigation lights and strobe locations. My Captain wrote again all five Navigation lights and the Airplane was again AOG.  The mechanic arrived shortly and worked with Maintenance Control and [company] to authorize the operation of the airplane under a Manufacturer's Guidance Letter that allowed water near LED lights and associated power sources in the NAV light and strobe light positions. Realizing that the Company didn't notify the FSDO; or other branch of the FAA to get authorization for this Guidance Letter; I agreed with my Captain to file this report to get the FAA oversight on this issue.  [Recommend] more communication from the company to the crew about the procedure under which a Guidance Letter is put in place to get an aircraft flying after a situation like this has been noticed. [Improper] maintenance procedures.
A Captain and First Officer report their Air Carrier has been using a Guidance letter from the aircraft's Manufacturer not yet approved by the FAA; to dispatch their aircraft with water/moisture condensation at LED lights and associated power sources in the sealed Navigation; Strobe; Beacon; and Emergency light positions. Letter had not been included in their Aircraft's Flight Manual (AFM) to allow proper dispatch.