[Federal Register Volume 61, Number 206 (Wednesday, October 23, 1996)]
[Proposed Rules]
[Pages 54955-54958]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27125]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 61, No. 206 / Wednesday, October 23, 1996 / 
Proposed Rules  

[[Page 54955]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-65-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A300-600 and A310 Series 
Airplanes Equipped With Pre-Modification 5844D4829 Rudders

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Airbus Model A300-
600 and A310 series airplanes, that currently requires repetitive 
visual inspections and tap tests of the rudder skin panels to detect 
disbonding; and repairs, if necessary. That AD was prompted by reports 
of weakening of the bonding material between the core of the rudder and 
its inner and outer skin, and cracking of the core. The proposed action 
would add repetitive elasticity laminate checker (ELCH) inspections of 
the rudder in place of the currently required tap tests. It also would 
require replacement of the rudder with a modified rudder, which would 
terminate the repetitive inspections. These actions are intended to 
detect and prevent disbonding of the rudder, which, if not corrected, 
could reduce the structural integrity of the rudder, and consequently 
lead to a reduction in its ability to sustain limit loads.

DATES: Comments must be received by December 2, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-65-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule may be 
obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 
Blagnac Cedex, France. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Tim Backman, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2797; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-65-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-65-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On May 25, 1990, the FAA issued AD 90-12-13, amendment 39-6625 (55 
FR 23190, June 7, 1990), which is applicable to Airbus Model A300-600 
and A310 series airplanes equipped with pre-modification 5844D4829 
rudders. That AD requires repetitive visual inspections and tap tests 
of the rudder skin panels to detect disbonding and cracking; and 
repairs, if necessary. That AD was prompted by reports of disbonding 
and cracking in the layers of the rudder skin panels, as well as 
rupture of the honeycomb core of the rudder. The requirements of that 
AD are intended to prevent loss of stiffness in the rudder which, if 
not corrected, could reduce the structural integrity of the rudder, and 
consequently lead to a reduction in its ability to sustain limit loads.
    At the time AD 90-12-13 was issued, the FAA considered it to be 
interim action because the manufacturer was attempting to determine the 
extent and nature of the disbonding and cracking within the fleet, and 
was developing a repetitive inspection schedule. Additionally, the 
manufacturer had advised that it was developing a modification of the 
rudder that would preclude the need for repetitive inspections.

Actions Since Issuance of Previous AD

    Since the issuance of that AD, the Direction Generale de l'Aviation 
Civile (DGAC), which is the airworthiness authority for France, 
notified the FAA that it has received additional reports indicating 
that disbonding had occurred on certain Airbus Model A310 series 
airplanes between the inner skin and the honeycomb core of the rudder; 
this disbonding had led to cracking and rupture of the core and outer 
skin of the rudder. The affected airplanes had accumulated between 
9,500 and 15,000 hours time-in-service, and between 5,200 and 15,000 
flight cycles.
    Investigation has revealed that 80 Model A300-600 and A310 series 
airplanes, among the earliest manufactured, may have a rudder in which 
the bond between the honeycomb core and the inner and outer skins was 
made using a bridging layer of aramide carbon hybride laminate. 
Laboratory analysis has shown that flight cycles,

[[Page 54956]]

over time, gradually weaken this bond, leading to areas of disbonding 
and cracking, which can spread rapidly throughout the rudder. This 
condition, if not corrected, could reduce the structural integrity of 
the rudder, and consequently lead to a reduction in its ability to 
sustain limit loads.
    Additionally, the manufacturer recently has developed an elasticity 
laminate checker (ELCH) inspection, which relies on a vacuum principle 
to detect and assess areas of disbonding and cracking. This inspection, 
which can detect disbonding defects as small as 120 mm in diameter, is 
considered to be more reliable than the tap test that is currently 
required by AD 90-12-13.
    The manufacturer also has developed a modified rudder which, if 
installed, would eliminate the need for both types of repetitive 
inspections.

Explanation of Relevant Service Information

    Airbus has issued Service Bulletins A300-55-6008 (for Model A300-
600 series airplanes) and A310-55-2010 (for Model A310 series 
airplanes), both dated December 10, 1990, which describe procedures for 
repetitive visual and ELCH inspections of the rudder to detect 
disbonding. The service bulletins also describe procedures for repairs. 
The DGAC classified these service bulletins as mandatory, and issued 
French airworthiness directive (CN) 90-0098-112(B)R1, dated May 2, 
1991, in order to assure the continued airworthiness of these airplanes 
in France.
    Airbus also has issued Service Bulletins A300-55-6010 (for Model 
A300-600 series airplanes) and A310-55-2012 (for Model A310 series 
airplanes), both dated April 18, 1991, which describe procedures for 
replacement of the rudder with a modified rudder. Installation of the 
modified rudder will preclude the addressed cracking and disbonding 
problems, and will eliminate the need for repetitive inspections of the 
area for those defects. The DGAC classified these service bulletins as 
optional.

FAA's Conclusions

    These airplane models are manufactured in France and are type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the DGAC has kept the FAA informed 
of the situation described above. The FAA has examined the findings of 
the DGAC, reviewed all available information, and determined that AD 
action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would supersede AD 90-12-13 to 
continue to require repetitive visual inspections of the rudder skin 
panels. It would eliminate the currently required tap tests, and 
instead require ELCH inspections of the rudder skin panels. If defects 
are detected, repair would be required. All inspections and the repair 
of smaller areas of disbonding or cracking would be required to be 
carried out in accordance with the applicable inspection service 
bulletins described previously; repairs of the largest defective areas, 
however, would have to be performed in a manner approved by the FAA.
    Until an initial ELCH inspection of the complete rudder is 
performed, the proposal would require visual inspections of the rudder 
to be performed weekly or prior to the accumulation of 50 flight 
cycles, whichever occurs first. Thereafter, visual inspections would be 
carried out at less frequent intervals, as would subsequent ELCH 
inspections.
    Should a visual inspection prior to the initial ELCH inspection, 
however, detect possible disbonding or cracking, the proposed AD would 
require an ELCH inspection of the area in which the suspected defects 
may be located. If that ELCH inspection confirms any defects, repairs 
would be made prior to further flight. Regardless of the results of the 
ELCH inspection of the area in which suspected defects may be located, 
the proposal would still require that an initial ELCH inspection of the 
complete rudder be conducted.
    The proposed AD also would require replacement of the rudder with a 
rudder modified by the manufacturer; this action would constitute 
terminating action for the repetitive visual and ELCH inspections. The 
replacement of the rudder would be required to be accomplished in 
accordance with the applicable modification service bulletins described 
previously.

Difference Between Proposed Rule and Parallel French CN

    Unlike French CN 90-098-112(B)R1, which permits installation of the 
modified rudder as an optional terminating action, this proposed AD 
would require that the modified rudder be installed within 5 years, as 
terminating action for the inspections. The FAA has determined that 
long-term, continued operational safety will be better assured by 
modifications or design changes to remove the source of the problem, 
rather than by repetitive inspections. Long-term inspections may not be 
providing the degree of safety assurance necessary for the transport 
airplane fleet. This, coupled with a better understanding of the human 
factors associated with numerous repetitive inspections, has led the 
FAA to consider placing less emphasis on special procedures and more 
emphasis on design improvements. The proposed modification requirement 
is in consonance with these considerations.

Cost Impact

    There are approximately 44 Model A310 and Model A300-600 series 
airplanes of U.S. registry that would be affected by this proposed AD.
    The tap tests that are currently required by AD 90-12-13 take 
approximately 4 work hours per airplane to accomplish. The average 
labor rate is $60 per work hour. Based on these figures, the cost 
impact of these currently-required actions on U.S. operators is 
estimated to be $10,560, or $240 per airplane, per tap test.
    The visual inspections that are currently required by AD 90-12-13 
(and retained in this new proposed AD) take approximately 1 work hour 
per airplane to accomplish, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of these inspections on 
U.S. operators is estimated to be $2,640, or $60 per airplane, per 
inspection.
    Each ELCH inspection proposed in this new AD action would take 
approximately 14 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact these proposed inspections on U.S. operators is estimated to be 
$36,960, or $840 per airplane, per inspection.
    The replacement of the rudder that is proposed by this new AD 
action would take approximately 42 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of this proposed replacement action on 
U.S. operators is estimated to be $110,880, or $2,520 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator

[[Page 54957]]

would accomplish those actions in the future if this AD were not 
adopted.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 removing amendment 39-6625 (55 FR 
23190, June 7, 1990), and by adding a new airworthiness directive (AD), 
to read as follows:

Airbus Industrie: Docket 96-NM-65-AD. Supersedes AD 90-12-13, 
Amendment 39-6625.
    Applicability: Model A300-600 and A310 series airplanes; 
certificated in any category; equipped with pre-modification 
5844D4829 rudders having the following part numbers:

A5547150000000
A5547150000200
A5547150000400
A5547150000600
A5547150000800
A5547150001000
A5547150001200
A5547150001400

    Note 1: The pre-modification rudders to which this AD applies 
were installed at the time of delivery on Model A300-600 and A310 
series airplanes specified in the effectivity listings of the Airbus 
service bulletins that are referenced in this AD. However, such 
rudders may have been installed after delivery on airplanes other 
than the ones listed in those service bulletins. Therefore, as 
specified by the preceding applicability provision, the operator of 
any Model A300-600 or A310 series airplane equipped with the pre-
modified rudder is required to comply with the requirements of this 
AD.

    Note 2: 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 (f) 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.

    Note 3: The requirements of paragraphs (a) and (b) of this AD 
are restatements of paragraphs A. and B. that appeared in AD 90-12-
13, amendment 39-6625. These paragraphs require no additional action 
by operators who already have initiated the specified actions. (As 
indicated in both paragraphs, these actions are to continue until 
the new actions required by this AD are initiated.)

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and prevent disbonding which, if not corrected, could 
reduce the structural integrity of the rudder, and consequently lead 
to a reduction in its ability to sustain limit loads, accomplish the 
following:
    (a) Visual Inspections (as Required by AD 90-12-13). Within 10 
landings after June 20, 1990 (the effective date of AD 90-12-13, 
amendment 39-6625), perform a visual inspection to detect disbonding 
of the rudder skin panels, left and right, in accordance with Airbus 
All Operators' Telex (AOT) 55/90/01, Revision 1, dated April 27, 
1990. After the effective date of this AD, perform this inspection 
in accordance with Airbus Service Bulletin A300-55-6008 (for Airbus 
Model A300-600 series airplanes), or Airbus Service Bulletin A310-
55-2010 (for Airbus Model A310 series airplanes), both dated 
December 10, 1990, as applicable.
    (1) If no defects are found, repeat the visual inspection 
thereafter at intervals not to exceed 7 days or 50 landings, 
whichever occurs first, until the requirements of paragraph (c) of 
this AD are initiated.
    (2) If defects are found, prior to further flight, perform a tap 
test in accordance with paragraph (b) of this AD.
    (b) Tap Tests (as Required by AD 90-12-13). Within 300 landings 
after June 20, 1990, perform a tap test to determine the extent of 
the damage, in accordance with Airbus AOT 55/90/01, Revision 1, 
dated April 27, 1990.
    (1) If disbonding is less than 100 square cm, repeat the tap 
test of the affected area every 28 days or 200 landings, whichever 
occurs first, until the ELCH inspection requirements of paragraph 
(d) of this AD are initiated. For any signs of additional rudder 
skin panel disbonding, perform drilling procedures in accordance 
with paragraph 4.2.2.3. of the AOT; and thereafter repeat the visual 
inspection of the rudder skin panels specified in paragraph (a) of 
this AD, until the ELCH inspection requirements of paragraph (d) of 
this AD are initiated.
    (2) If disbonding is more than 100 square cm, but less than 
5,000 square cm, repair in accordance with paragraph 4.2.2.3. of the 
AOT. Thereafter, repeat the visual inspection of the rudder skin 
panels in accordance with paragraph (a) of this AD; and perform 
repetitive tap tests of the repaired areas at the following 
intervals; until the visual inspection requirements of paragraph (c) 
of this AD are initiated:
    (i) Perform the tap test of the repaired area every 500 landings 
for disbonding greater than 100 square cm but less than 300 square 
cm;
    (ii) Perform the tap test of the repaired area every 250 
landings for disbonding greater than 300 square cm, but less than 
1,000 square cm;
    (iii) Perform the tap test of the repaired area every 75 
landings for disbonding that is greater than 1,000 square cm, but 
less than 5,000 square cm.
    (3) If disbonding is greater than 5,000 square cm, or if a crack 
is found, prior to further flight, repair in a manner approved by 
the Manager, Standardization Branch, ANM-113, FAA, Transport 
Airplane Directorate.
    (c) New Visual Inspection Requirement. Perform a visual 
inspection of the complete rudder to detect disbonding and cracking 
of the rudder skin panels, left and right, in accordance with Airbus 
Service Bulletin A300-55-6008 (for Airbus Model A300-600 series 
airplanes), or Airbus Service Bulletin A310-55-2010 (for Airbus 
Model A310 series airplanes), both dated December 10, 1990, as 
applicable. Initiation of this inspection constitutes terminating 
action for the requirements of paragraph (a) and specified portions 
of paragraph (b) of this AD.
    (1) Perform the initial inspection at the later of the times 
specified in paragraph (c)(1)(i) or (c)(1)(ii) of this AD:
    (i) Within 7 days or 50 landings after the effective date of 
this AD, whichever is first; or
    (ii) Within 7 days or 50 landings whichever occurs first after 
the last visual inspection performed in accordance with AD 90-12-13, 
amendment 39-6625.
    (2) If no disbonding or cracking is detected during this 
inspection accomplish the actions specified in paragraphs (c)(2)(i) 
and (c)(2)(ii) of this AD:
    (i) Repeat the visual inspection at intervals not to exceed 7 
days or 50 landings,

[[Page 54958]]

whichever occurs first, until the initial ELCH inspection is 
accomplished in accordance with paragraph (d) of this AD. And
    (ii) After the initial ELCH inspection required by paragraph (d) 
of this AD has been accomplished, repeat these visual inspections 
thereafter at intervals not to exceed 350 landings, in accordance 
with the applicable service bulletin.
    (3) If any disbonding or cracking is detected, prior to further 
flight, conduct an ELCH inspection of the suspected area for signs 
of disbonding, and accomplish follow-on actions in accordance with 
the Flow Chart, Figure 2, of the applicable service bulletin. If the 
confirmed extent of disbonding, however, is greater than 400 square 
cm in Area I, or greater than 800 square cm in Area II, as those 
areas of the rudder are defined in the applicable service bulletin, 
prior to further flight, repair and accomplish subsequent 
inspections in accordance with the requirements of paragraph (d)(3) 
of this AD.
    (d) ELCH Inspections. Within 6 months after the effective date 
of this AD, conduct an initial elasticity laminate checker (ELCH) 
inspection of the complete rudder, in accordance with Airbus Service 
Bulletin A300-55-6008 (for Model A300-600 series airplanes) or 
Airbus Service Bulletin A310-55-2008 (for Model A310 series 
airplanes), both dated December 10, 1990, as applicable. Initiation 
of this inspection constitutes terminating action for the 
requirements of paragraph (a) and specified portions of paragraph 
(b) of this AD.
    (1) If no disbonding or cracking is detected, repeat the ELCH 
inspection at intervals not to exceed 2 years or 3,500 landings, 
whichever occurs first.
    (2) If disbonding or cracking is confirmed by ELCH inspection, 
and the extent of the disbonding is equal to or less than 400 square 
cm in Area I, or equal to or less than 800 square cm in Area II, as 
those areas of the rudder are defined in the applicable service 
bulletin: Prior to further flight, accomplish follow-on actions in 
accordance with Flow Chart, Figure 2, of the applicable service 
bulletin.
    (3) If disbonding or cracking is confirmed by ELCH inspection, 
and the extent of the disbonding is greater than 400 square cm in 
Area I, or greater than 800 square cm in Area II, as those areas of 
the rudder are defined in the applicable service bulletin: Prior to 
further flight, accomplish either paragraph (d)(3)(i) or (d)(3)(ii) 
of this AD:
    (1) Repair in a manner approved by the Manager, Standardization 
Branch, ANM-113, FAA, Transport Airplane Directorate. Thereafter, 
continue to conduct ELCH inspections in a manner and at intervals 
approved by the Manager, Standardization Branch, ANM-113.
    (ii) Replace the rudder in accordance with Airbus Service 
Bulletin A300-55-6010 (for Model A300-600 series airplanes) or 
Airbus Service Bulletin A310-55 2012 (for Model A310 series 
airplanes), both dated April 18, 1991, as applicable. After this 
replacement is accomplished, no further actions are required by this 
AD.
    (e) Terminating Action. Within five years after the effective 
date of this AD, replace the rudder in accordance with Airbus 
Service Bulletin A300-55-6010 (for Model A300-600 series airplanes) 
or Airbus Service Bulletin A310-55 2012 (for Model A310 series 
airplanes), both dated April 18, 1991, as applicable. This 
replacement constitutes terminating action for the inspection 
requirements of this AD.
    (f) 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, Standardization Branch, ANM-113. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Standardization Branch, ANM-113.

    sNote 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, Standardization Branch, ANM-113.

    (g) 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.

    Issued in Renton, Washington, on October 16, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27125 Filed 10-22-96; 8:45 am]
BILLING CODE 4910-13-U