Number/ Apollo Fox 001
Affected airplanes/ all Apollo Fox equipped with
composite streamlined wing strut cover
Issue date/ 2023.04.04
Reason of issue/ possible surface corrosion on the wing
struts top part
Suggested completion date as early as possible
but at least 2 weeks after receiving this bulletin or before the next
Surface corrosion was observed on the wing struts at one particular
Apollo Fox during regular check at the top part of wingstruts. After
dismentled and cutted the struts it was identified that the corrosion is
exclusively found on the outer surface where the composite streamlined
wing strut cover met the steel tube strut in about 2 cm lenght. The
airplane is 19 year old, one year before mandatory complete overhaul.
The corrosion is minor, only on the surface, and even in the case of
complete neglect, it is unlikely that in the one year remaining until
the overhaul, the level of corrosion has increased to such an extent
that the structural strength and safety of the aircraft would
deteriorate even with the smallest degree. Regardless of this, we
consider it necessary to carry out an inspection of the given structural
element, with the utmost regard for flight safety.
Detilas of the inspection:
The owner, pilot, and or maintenance person of the aircraft must check
that the water outlet drain hole in the lower part of the composite
wingstrut cover is clean and passable! If it is not, the drain hole must
be cleaned to ensure its permeability, so that any condensate,
rainwater, or liquid of any kind that may have accumulated in the wing
strut can continuously drain from the bottom, and in no case accumulate
in the struts.
The sealing paste in the upper part of the duct line must be removed,
and it must be checked that there is any rusting and corrosion under the
paste, in its vicinity, on the strut. If it is not found, then the end
of the strut must be closed repeatedly with non corrosive acril paste.
Only and exclusively non corrosive acril paste can be used. Other pastes
corrosive materials can cause damage the steel strut!
If surface corrosion can be detected on the strut, it must be removed by
spraying it with Würth Boltex rust-dissolving aerosol, the rust-free
surface must be repainted with dual component acril paint and the end of
composite wing strut cover must be closed and sealed with acril non
If it found the corrosion is not of a superficial nature, then notify
Főnix Repülőgépgyár Kft.