SUBJECT:
Thermal/Acoustic Insulation Installed on Transport Category
Airplanes
REFERENCE: Federal Register: December 30, 2005
(Volume 70, Number 250)
SUMMARY: This FAA action modifies the
requirements for improved flammability characteristics of
thermal/acoustic insulation used as replacements on airplanes
manufactured before September 2, 2005.
Major Highlights
Amendments to parts 91, 121, 125, and 135 require that
insulation materials, when installed as replacements, meet the new
flame propagation test requirements of Sec. 25.856.
Following publication of the final rule, and the associated
Advisory Circular (AC) 25.856-1, and shortly before the September
2, 2005, compliance date, industry representatives (including AEA)
told the FAA that some assumptions in the regulation were not
correct.
For a number of reasons
presented by the General Aviation community, the FAA has
significantly changed the regulations affecting in-service
aircraft. The rule now is limited to insulation blankets and
removable insulation on ducting.
The materials in insulation blankets were one of the primary
materials intended to be covered by the "replacement" provision in
the regulation and continue to be covered by the rule.
In addition, insulation around ducts is significant for its
potential fire safety ramifications. Ducts are intended to convey a
fluid medium from one point to others and, therefore, provide a
potential fire propagation path by their nature. Because air ducts
are the most significant and common, the FAA is limiting the
replacement provision in this amendment to insulation air ducts
only.
Other types of piping, or fluid lines are no longer covered by
the replacement provision. These items, which might otherwise be
considered ducts, are not included in this amendment because they
have very specialized insulation needs, and replacement parts are
not readily available. In addition, they tend to be much smaller
than air ducts and do not use the large quantity of insulation that
was the target of the original proposal.
While some ducts and insulation are integral, meaning that
replacement of the insulation includes the replacement of the duct,
many ducts are insulated with separate materials. The July 2003
rule will continue to apply to those ducts insulated with separate
material. However, insulation that is integral to the duct and
cannot be replaced without replacing the duct will no longer be
covered by the regulations for replacement. This includes
insulation that is bonded or laminated to the surface of the
duct.
The regulation now reads:
Sec. 91.613 Materials for compartment interiors.
(b) Thermal/acoustic insulation materials. For transport
category airplanes type certificated after January 1, 1958:
(1) For airplanes manufactured before September 2, 2005, when
thermal/acoustic insulation is installed in the fuselage as
replacements after September 2, 2005, the insulation must meet the
flame propagation requirements of Sec. 25.856 of this chapter,
effective September 2, 2003, if it is:
(i) Of a blanket
construction or
(ii) Installed around air ducting.
(NOTE: Sections. 91.613(b)(1), 121.312(e)(1), 125.113(c)(1), and
135.170(c)(1) have all been amended with similar language.)
This final rule is effective on January 30, 2006. Send your
comments by February 28, 2006.
AEA Commentary
AEA is very pleased with the FAA's efforts to amend these
regulations. The amendment is very appropriate and reasonable.
However, the Association continues to be disappointed with the
Agency for not addressing the hundreds of Parts catalogs which
contain hundreds of part numbers which are no longer acceptable for
use on U.S. registered aircraft.
The author of these regulations makes the in-appropriate
assumption that a maintenance technician will review the aircraft
operating rules prior to ordering replacement parts for an
aircraft.
To help prevent the technicians from ordering and installing
non-compliant parts, AEA is encouraging its members to share the
information contained in this Regulatory Update with the entire
maintenance organization.