DATE: July 20, 2018
AD #: 2018-15-51
This Emergency Airworthiness Directive (AD) 2018-15-51 is being sent to
owners and operators of Bell Helicopter Textron Canada Limited (Bell)
Model 429 helicopters.
This emergency AD was prompted by two reports of tail rotor (T/R) gearbox
assemblies loosely attached to the gearbox support. This emergency AD
requires inspecting the T/R gearbox installation for looseness, visually
inspecting the T/R gearbox retaining hardware and support attachment point
areas, and torque inspecting the gearbox retaining nuts. The actions in
this emergency AD are intended to prevent detachment of the T/R gearbox,
loss of T/R control, and loss of control of the helicopter.
Transport Canada, which is the aviation authority for Canada, has issued
Canadian Emergency AD No. CF-2018-18, dated July 11, 2018, to correct
an unsafe condition for Bell Model 429 helicopters. Transport Canada advises
of two reports of T/R gearbox assemblies loosely attached to the gearbox
support. According to Transport Canada, this condition could lead to structural
damage and possible loss of control of the helicopter.
This model helicopter has been approved by the aviation authority of Canada
and is approved for operation in the United States. Pursuant to our bilateral
agreement with Canada, Transport Canada, its technical representative,
has notified us of the unsafe condition described in the Transport Canada
AD. We are issuing this AD because we evaluated all information provided
by Transport Canada and determined the unsafe condition exists and is
likely to exist or develop on other helicopters of the same type design.
Related Service Information
We reviewed Bell Alert Service Bulletin 429-18-40, dated July 6, 2018,
which specifies a one-time inspection of the T/R gearbox installation
and a one-time visual and torque inspection of the six installation attachment
points. This service information also specifies contacting Bell Product
Support Engineering with the results of the T/R gearbox installation inspection,
any findings of the visual inspection, and the results of the torque inspection.
Emergency AD Requirements
This emergency AD requires inspecting the T/R gearbox installation for
looseness, visually inspecting the T/R gearbox retaining hardware and
each support attachment point area, and torque inspecting each gearbox
retaining nut. Depending on the inspection results, this emergency AD
requires replacing or repairing the affected parts in accordance with
Differences Between This Emergency AD and the Transport Canada AD
The Transport Canada AD applies to helicopters with specific serial numbers,
whereas this emergency AD applies to all Model 429 helicopters. The Transport
Canada AD includes a calendar-based compliance time, whereas this emergency
AD does not. The Transport Canada AD requires reporting certain information
to Bell Product Support Engineering and this emergency AD does not. If
there is looseness, this emergency AD requires performing the visual inspection
and torque inspection before further flight, while the Transport Canada
AD requires contacting Bell. Lastly, if the torque of a T/R gearbox retaining
nut is below 160 in-lbs (19 Nm), this emergency AD requires removing the
T/R gearbox and inspecting the mounting surfaces and retaining hardware,
while the Transport Canada AD requires contacting Bell.
We consider this emergency AD to be an interim action. If final action
is later identified, we might consider further rulemaking then.
Authority for this Rulemaking
Title 49 of the United States Code specifies the FAA’s authority to issue
rules on aviation safety. Subtitle I, Section 106, describes the authority
of the FAA Administrator. “Subtitle VII, Aviation Programs,” describes
in more detail the scope of the Agency’s authority.
We are issuing this rulemaking under the authority described in “Subtitle
VII, Part A, Subpart III, Section 44701, General requirements.” Under
that section, Congress charges the FAA with promoting safe flight of civil
aircraft in air commerce by prescribing regulations for practices, methods,
and procedures the Administrator finds necessary for safety in air commerce.
This regulation is within the scope of that authority because it addresses
an unsafe condition that is likely to exist or develop on products identified
in this rulemaking action.
Adoption of the Emergency Airworthiness Directive (AD)
We are issuing this Emergency AD under 49 U.S.C. Sections 106(g), 40113,
and 44701 according to the authority delegated to me by the Administrator.