[Federal Register Volume 63, Number 109 (Monday, June 8, 1998)]
[Proposed Rules]
[Pages 31142-31143]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-15135]



[[Page 31142]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-160-AD]
RIN 2120-AA64


Airworthiness Directives; Construcciones Aeronauticas, S.A. 
(CASA) Model CN-235 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all CASA Model CN-235 series 
airplanes. This proposal would require repetitive high frequency eddy 
current (HFEC) inspections of the flap transmission shafts to detect 
cracking, and repetitive functional tests (checks) to verify proper 
operation of the flap braking sub-system; and corrective actions, if 
necessary. This proposal is prompted by issuance of mandatory 
continuing airworthiness information by a foreign civil airworthiness 
authority. The actions specified by the proposed AD are intended to 
detect and correct cracking in the flap transmission shafts, and to 
correct a malfunctioning flap braking sub-system, which could result in 
the inability to move the flaps, or in an asymmetric flap condition, 
and consequent reduced controllability of the airplane.

DATES: Comments must be received by July 8, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-160-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 Construcciones Aeronauticas, S.A., Getafe, Madrid, Spain. 
This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; fax (425) 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 98-NM-160-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-114, Attention: Rules 
Docket No. 98-NM-160-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Direccion General de Aviacion (DGAC), which is the 
airworthiness authority for Spain, notified the FAA that an unsafe 
condition may exist on all CASA Model CN-235 series airplanes. The DGAC 
advises that, on three Model CN-235 series airplanes that had 
accumulated a high number of landings, cracks were detected around the 
heads of the rivets on the ends of the flap transmission shafts. These 
cracks start at the rivet hole and grow radially. The cracks are 
attributed to fatigue, which could have resulted from a malfunctioning 
flap braking sub-system, and consequent high loads on the transmission 
shafts. Such cracking, if not corrected, could result in the inability 
to move the flaps, or in an asymmetric flap condition, and consequent 
reduced controllability of the airplane.

Explanation of Relevant Service Information

    The manufacturer has issued CASA Maintenance Instructions COM 235-
113, Revision 02, dated June 16, 1997, including Annex I, dated June 
16, 1997, and Annex II, dated July 1, 1997. The maintenance 
instructions describe procedures for repetitive high frequency eddy 
current (HFEC) inspections of the flap transmission shafts to detect 
cracking; replacement of any cracked shaft with a new or serviceable 
shaft; repetitive functional tests (checks) of the flap braking sub-
system to verify proper operation; and replacement of any discrepant 
brake with a new or serviceable brake. Accomplishment of the actions 
specified in the maintenance instructions is intended to adequately 
address the identified unsafe condition. The DGAC classified these 
maintenance instructions as mandatory and issued Spanish airworthiness 
directive 11/96, Revision 1, dated June 19, 1997, in order to assure 
the continued airworthiness of these airplanes in Spain.

FAA's Conclusions

    This airplane model is manufactured in Spain and is 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 require accomplishment of 
actions specified in the maintenance instructions described previously, 
except as discussed below.

Differences Between the Proposed Rule and the Related Service 
Information

    This proposed AD would require compliance in terms of landings 
accumulated on the airplane, whereas the Spanish airworthiness 
directive requires compliance based on the number of landings 
accumulated on

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individual flap transmission shafts. The FAA does not consider it 
practicable for U.S. operators to accomplish an inspection program that 
necessitates tracking the landings accumulated on individual flap 
transmission shaft components due to the difficulty of such tracking.
    Operators should further note that, unlike the procedures described 
in the maintenance instructions, this proposed AD would not permit 
further flight if cracks are detected in the flap transmission shaft. 
The FAA has determined that, because of the safety implications and 
consequences associated with such cracking, any subject flap 
transmission shaft that is found to be cracked must be repaired or 
modified prior to further flight.

Cost Impact

    The FAA estimates that 2 airplanes of U.S. registry would be 
affected by this proposed AD, and that it would take approximately 30 
work hours per airplane to accomplish the proposed inspection and 
functional test, at an average labor rate of $60 per work hour. Based 
on these figures, the cost impact proposed by this AD on U.S. operators 
is estimated to be $3,600, or $1,800 per airplane, per cycle.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed 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 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 adding the following new 
airworthiness directive:

Construcciones Aeronauticas, S.A. (CASA): Docket 98-NM-160-AD.

    Applicability: All CASA Model CN-235 series airplanes, 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (c) 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 detect and correct cracking in the flap transmission shafts, 
and to correct a malfunctioning flap braking sub-system, which could 
result in the inability to move the flaps, or in an asymmetric flap 
condition, and consequent reduced controllability of the airplane; 
accomplish the following:
    (a) Prior to the accumulation of 6,000 total landings, or within 
30 days after the effective date of this AD, whichever occurs later, 
perform a high frequency eddy current (HFEC) inspection of the flap 
transmission shafts to detect cracking, in accordance with
    Annex I, dated June 16, 1997, of CASA Maintenance Instructions 
COM 235-113, Revision 02, dated June 16, 1997.
    (1) If no cracking is detected, repeat the HFEC inspection 
thereafter at intervals not to exceed 2,000 landings.
    (2) If any cracking is detected, prior to further flight, 
replace the cracked shaft with a new or serviceable shaft, in 
accordance with the maintenance instructions; and repeat the HFEC 
inspection thereafter at intervals not to exceed 2,000 landings.
    (b) Prior to the accumulation of 6,000 total landings, or within 
30 days after the effective date of this AD, whichever occurs later, 
perform a functional test (check) to verify proper operation of the 
flap braking sub-system, in accordance with Annex II, dated July 1, 
1997, of CASA Maintenance Instructions COM 235-113, Revision 02, 
dated June 16, 1997.
    (1) If no malfunction is detected, repeat the functional test 
thereafter at intervals not to exceed 300 landings.
    (2) If any malfunction is detected, prior to further flight, 
replace any discrepant component with a new or serviceable component 
in accordance with the maintenance instructions; and repeat the 
functional test to verify proper operation of the flap braking sub-
system; thereafter, repeat the functional test thereafter at 
intervals not to exceed 300 landings.
    (c) 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, International Branch, ANM-116, FAA, 
Transport Airplane Directorate. Operators shall submit their request 
through an appropriate FAA Principal Maintenance Inspector, who may 
add comments and then send it to the Manager, International Branch, 
ANM-116.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (d) 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.

    Note 3: The subject of this AD is addressed in Spanish 
airworthiness directive 11/96, Revision 1, dated June 19, 1997.

    Issued in Renton, Washington, on June 2, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-15135 Filed 6-5-98; 8:45 am]
BILLING CODE 4910-13-U