INFORMATION LETTER #2002-1
S-61/H-3 Tail Rotor Blade Corrosion
has received tail rotor blades part number S6117-30101 and S6117-30201
from various operators for repair. This blade has an additional balance
weight system in under the root-end filler to provide an additional
cord-wise balance means. The root-end filler is still manufactured
from balsa wood and sealed with clear lacquer.
blades have been received with the balsa insert sealed with structural
adhesive, this will make inspection in the field almost impossible.
When you inspect this area of the blade you apply finger pressure to
the filler to determine if it is soft, if so you replace this filler
I/A/W your Sikorsky maintenance manual, see below figure 4-20. With
the filler sealed with structural adhesive it is always hard to the
touch but the adhesive will dis-bond from the sides of the root-channel
allowing moisture to enter the cavity.
seen in the picture below the balsa filler holds the moisture in this
area and now you may have corrosion. The blade in the illustration
now will have to have the pocket, strap and root channel replaced and
if this problem was not addressed the blade may be scrap do to the
corrosion damage to the spar.
notice is for information purposes only and does not condemn any blade
without a more detailed inspection.
tail rotor blades that the balsa filler has deteriorated and has moisture
present, take additional labor to repair and static balance due to
the corrosion of the balance weight retaining bolt. Many of these blades
will have to have the screw drilled out with out damaging the nut plate.
The nut plate is installed in the root channel prior to installing
the assembly in the blade. To replace the root channel in most circumstances
the pocket will need replacing also.
more information be desired please phone Dave Stutesman at ABS 407-846-6780.