[Federal Register Volume 62, Number 17 (Monday, January 27, 1997)]
[Rules and Regulations]
[Pages 3784-3786]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1826]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-192-AD; Amendment 39-9906; AD 97-02-21]
RIN 2120-AA64
Airworthiness Directives; Empresa Brasileira de Aeronautica, S.A.
(EMBRAER) Model EMB-120 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain EMBRAER Model EMB-120 series airplanes, that
requires repetitive inspections to detect cracks in the wing rib-to-
skin support brackets (shear clips), and replacement of cracked
brackets with new or serviceable brackets. This amendment also requires
the eventual replacement of certain brackets with new brackets, which
terminates the requirement for the inspections. This amendment is
prompted by reports of cracks in certain wing rib-to-skin support
brackets in both the lower and upper skin of the wings. The actions
specified by this AD are intended to prevent cracking of those support
brackets, which can subsequently lead to the loosening of the rivets in
the wing skin, leakage of fuel through the rivet holes, and,
ultimately, the reduction of the structural integrity of the wing.
DATES: Effective March 3, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of March 3, 1997.
ADDRESSES: The service information referenced in this AD may be
obtained from Empresa Brasileira de Aeronautica, S.A. (EMBRAER), Sao
Jose dos Campos--SP, Brazil. This information may be examined at the
Federal Aviation Administration (FAA), Transport Airplane Directorate,
Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA,
Atlanta Aircraft Certification Office, Small Airplane Directorate,
Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park,
Georgia; or at the Office of the Federal Register, 800 North Capitol
Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Curtis Jackson, Aerospace Engineer,
Airframe and Propulsion Branch, ACE-117A, FAA, Atlanta Aircraft
Certification Office, Small Airplane Directorate, Campus Building, 1701
Columbia Avenue, Suite 2-160, College Park, Georgia 30337-2748;
telephone (404) 305-7358; fax (404) 305-7348.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to certain EMBRAER Model EMB-120
series airplanes was published in the Federal Register on April 24,
1996 (61 FR 17853). That action proposed to require repetitive
inspections to detect cracks in the wing rib-to-skin support brackets
(shear clips), and replacement of cracked brackets with new or
serviceable brackets. That action also proposed to require the eventual
replacement of certain brackets with new brackets, which would
terminate the requirement for the inspections.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the single comment received.
Request to Delete Inspection Requirement
The only commenter, a U.S. operator, requests that the proposal be
revised to delete the requirement to conduct repetitive inspections of
the brackets. This commenter states that the subject area already is
inspected by its flight crews on preflight inspections, and by its
mechanics on daily inspections and line checks. The commenter considers
that the need for the inspection requirement, and the extra paperwork
that would be involved, cannot be justified by any data. This
commenter, who operates 63 of the affected airplanes, indicates that it
has analyzed the last 12 months of data on fuel leaks in its fleet; the
data indicate that there have been 43 fuel leaks associated with
leaking rivets, but there were no broken or cracked brackets found.
The FAA does not concur with the commenter's request. While this
commenter specifically may not have found cracked brackets, there have
been several cases reported by other operators in which fuel leaks
caused by broken or cracked brackets were discovered on in-service
airplanes. The FAA finds that the proposed inspection requirement will
be effective in finding and addressing fuel leakage, and any associated
cracking of a support bracket, well before more serious problems
associated with these conditions could occur. The FAA also points out
that operators may discontinue the inspections once the newly designed
brackets are installed and follow-on actions are accomplished.
Request to Clarify ``New'' and ``Old'' Bracket Design
This same commenter requests clarification regarding the types of
replacement brackets that are required to be installed. Specifically,
the commenter questions whether it would be acceptable to install ``old
style'' brackets as replacement parts in cases where no ``new style''
brackets are available.
The FAA concurs that clarification is necessary. If cracking is
found in the brackets at ribs 15, 16, or 18, and the extent of the
cracking necessitates replacement, operators may install either another
new or serviceable ``old style'' bracket having the same part number;
or a ``new style'' bracket, having a part number that is specified in
paragraph 3.1. of EMBRAER Service Bulletin 120-57-0031. However,
terminating action consists of replacing
[[Page 3785]]
those brackets at ribs 15, 16, and 18 with only the ``new style''
brackets.
On the other hand, if cracking is found in brackets at other rib
locations (namely, ribs 19, 20, 21, and 22), only the ``old style''
brackets (same part number) are required to be installed as replacement
parts at those locations.
The final rule has been revised to clarify these points.
Revision of Format of Final Rule
The format of the final rule has been revised somewhat to follow
more closely the format of procedures as they are presented in the
referenced EMBRAER Service Bulletin 120-57-0031, dated July 6, 1995.
The FAA considers that this reformatting will help to clarify the
required procedures for affected operators.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes previously
described. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
The FAA estimates that 169 airplanes of U.S. registry will be
affected by this AD.
It will take approximately 6 work hours per airplane to accomplish
the required visual inspection for cracking, at an average labor rate
of $60 per work hour. Based on these figures, the cost impact of the
inspection action on U.S. operators is estimated to be $60,840, or $360
per airplane, per inspection cycle.
It will take approximately 56 work hours to accomplish the required
replacement of support brackets, at an average labor rate of $60 per
work hour. Required parts will cost approximately $1,000 per airplane.
Based on these figures, the cost impact of the replacement action on
U.S. operators is estimated to be $736,840, or $4,360 per airplane.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the requirements of this
AD action, and that no operator would accomplish those actions in the
future if this AD were not adopted.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
97-02-21 Embraer: Amendment 39-9906. Docket 95-NM-192-AD.
Applicability: Model EMB-120 airplanes, serial numbers 120001,
120003, 120004, and 120006 through 120304 inclusive; certificated in
any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (e) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent reduced wing structural integrity and fuel leakage of
the wing due to cracking of wing rib-to-skin support brackets,
accomplish the following:
Note 2: The term ``fuel leakage'' and ``stain,'' as used
throughout this AD, are used as they are defined and classified in
Chapter 28, Fuel, of the Airplane Maintenance Manual (AMM).
(a) Within 10 days after the effective date of this AD: Perform
a visual inspection of the wing skin along rib lines 15 and 16 to
detect any fuel leakage other than a stain. Thereafter, repeat this
inspection every 50 flight hours until the requirements of paragraph
(d) of this AD are accomplished.
(b) As a result of the inspection required by paragraph (a) of
this AD, accomplish either paragraph (b)(1) or (b)(2), as
applicable:
(1) If fuel leakage is detected during any inspection required
by paragraph (a) of this AD: Within 50 flights after detection of
fuel leakage, perform an internal visual inspection to detect
cracking of the wing rib-to-skin support brackets (shear clips) that
connect the lower and upper wing skins to ribs 15 and 16, in
accordance with the Accomplishment Instructions, PART I, of EMBRAER
Service Bulletin 120-57-0031, dated July 6, 1995.
(2) If no fuel leakage is detected during any inspection
required by paragraph (a) of this AD: At the applicable time
specified in paragraph (b)(2)(i) through (b)(2)(iv) of this AD,
perform an internal visual inspection to detect cracking of the wing
rib-to-skin support brackets (shear clips) that connect the lower
and upper wing skins to ribs 15 and 16, in accordance with the
Accomplishment Instructions, PART I, of EMBRAER Service Bulletin
120-57-0031, dated July 6, 1995.
(i) For airplanes that have accumulated less than 4,000 total
flight cycles as of the effective date of this AD: Inspect prior to
the accumulation of 5,200 total flight cycles, or within 1,200
flight cycles after the effective date of this AD, whichever occurs
later.
(ii) For airplanes that have accumulated 4,000 or more total
flight cycles, but less than 8,000 total flight cycles as of the
effective date of this AD: Inspect within 1,200 flight cycles after
the effective date of this AD.
(iii) For airplanes that have accumulated 8,000 or more total
flight cycles, but less than 12,000 total flight cycles as of the
effective date of this AD: Inspect within 800 flight cycles after
the effective date of this AD.
(iv) For airplanes that have accumulated 12,000 or more total
flight cycles as of the effective date of this AD: Inspect within
400 flight cycles after the effective date of this AD.
(c) As a result of the internal visual inspection to detect
cracking of the wing rib-to-skin support brackets (shear clips) that
connect the lower and upper wing skins to ribs 15 and 16, as
required by paragraph (b) of this AD, accomplish the actions
specified in paragraph (c)(1), (c)(2), or (c)(3), as applicable:
[[Page 3786]]
(1) If no cracking is detected: Repeat that internal visual
inspection thereafter at intervals not to exceed 1,200 flight cycles
until the requirements of paragraph (d) of this AD are accomplished.
(2) If any cracking is detected in only one wing skin support
bracket, and that cracking is more than half the length of the
bracket; and if any cracking also is detected in up to two
additional wing skin support brackets and that cracking is less than
half the length of the bracket: Repeat that internal visual
inspection thereafter at intervals not to exceed 400 flight cycles,
until the requirements of paragraph (d) of this AD are accomplished.
(3) If any cracking is detected other than that specified in
paragraph (c)(2) of this AD: Prior to further flight, replace any
support bracket that is cracked beyond the limits specified in
paragraph (c)(2) of this AD either with a new or serviceable bracket
having the same part number, or with a new style bracket having a
part number specified in paragraph 3.1. of EMBRAER Service Bulletin
120-57-0031, dated July 6, 1995.
Following replacement and prior to further flight, perform an
additional internal visual inspection to detect cracking of the
support brackets that connect the wing skins to ribs 18, 19, 20, 21,
and 22 in accordance with the EMBRAER service bulletin.
(i) If no cracking is found in the support brackets that connect
the wing skins at ribs 18, 19, 20, 21, or 22: Repeat that internal
visual inspection thereafter at intervals not to exceed 1,200 flight
cycles until the requirements of paragraph (d) of this AD are
accomplished.
(ii) If any cracking is found in the support brackets that
connect the wing skins at ribs 18, 19, 20, 21, or 22: Prior to
further flight, replace the cracked bracket with a new or
serviceable bracket having the same part number; rib 18 may also be
replaced with a ``new style'' bracket having a part number specified
in paragraph 3.1. of the EMBRAER service bulletin.
(d) Within 2 years after the effective date of this AD: Replace
all wing rib-to-skin support brackets of ribs 15, 16, and 18 with
``new style'' brackets having a part number specified in paragraph
3.1. of EMBRAER Service Bulletin 120-57-0031, dated July 6, 1995.
Replacement procedures shall be accomplished in accordance with the
Accomplishment Instructions, PART II, of that service bulletin.
Prior to further flight following that replacement, perform a visual
inspection to detect cracking of the wing skin support brackets of
ribs 19, 20, 21, and 22. If any cracking is found, prior to further
flight, replace the cracked bracket with a new or serviceable
bracket having the same part number, in accordance with the EMBRAER
service bulletin. Accomplishment of these actions constitutes
terminating action for the requirements of this AD.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Atlanta Aircraft Certification
Office (ACO), FAA, Small Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Atlanta ACO.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(g) The actions shall be done in accordance with EMBRAER Service
Bulletin 120-57-0031, dated July 6, 1995. This incorporation by
reference was approved by the Director of the Federal Register in
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be
obtained from Empresa Brasileira de Aeronautica, S.A. (EMBRAER), Sao
Jose dos Campos--SP, Brazil. Copies may be inspected at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Atlanta Aircraft Certification Office,
Small Airplane Directorate, Campus Building, 1701 Columbia Avenue,
Suite 2-160, College Park, Georgia; or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(h) This amendment becomes effective on March 3, 1997.
Issued in Renton, Washington, on January 17, 1997.
S. R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-1826 Filed 1-24-97; 8:45 am]
BILLING CODE 4910-13-U
