[Federal Register Volume 62, Number 212 (Monday, November 3, 1997)]
[Proposed Rules]
[Pages 59310-59313]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28984]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-CE-79-AD]
RIN 2120-AA64
Airworthiness Directives; American Champion Aircraft Corporation
7, 8, and 11 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to adopt a new airworthiness directive
(AD) that would apply to American Champion Aircraft Corporation (ACAC)
7, 8, and 11 series airplanes, excluding Model 8GCBC airplanes. The
Federal Aviation Administration (FAA) previously proposed similar AD
action for the ACAC Model 8GCBC airplanes. The proposed AD would
require installing inspection holes on the top and bottom wing
surfaces, repetitively inspecting the front and rear wood spars for
damage, repairing or replacing any damaged wood spar, and installing
inspection covers. Damage is defined as cracks; compression cracks;
longitudinal cracks through the bolt holes or nail holes; or loose or
missing rib nails. The proposed AD results from a review of the service
history of the affected airplanes that incorporate wood wing spars. The
review was prompted by in-flight wing structural failures on ACAC Model
8GCBC airplanes, and revealed several incidents where damage was found
on the front and rear wood spars on the affected airplanes. The actions
specified by the proposed AD are intended to prevent possible
compression cracks and other damage in the wood spar wing, which, if
not detected and corrected, could eventually result in in-flight
structural failure of the wing with consequent loss of the airplane.
DATES: Comments must be received on or before January 8, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Central Region, Office of the Regional Counsel,
Attention: Rules Docket No. 97-CE-79-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106. Comments may be inspected at this location
between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted.
Service information that applies to the proposed AD may be obtained
from American Champion Aircraft Corporation, P.O. Box 37, 32032
Washington Avenue, Highway D, Rochester, Wisconsin 53167. This
information also may be examined at the Rules Docket at the address
above.
FOR FURTHER INFORMATION CONTACT: Mr. William Rohder, Aerospace
Engineer, FAA, Chicago Aircraft Certification Office, 2300 E. Devon
Avenue, Des Plaines, Illinois 60018; telephone (847) 294-7697;
facsimile (847) 294-7834.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such
[[Page 59311]]
written data, views, or arguments as they may desire.
Communications should 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 that summarizes 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 No. 97-CE-79-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, Central Region, Office of the Regional Counsel, Attention:
Rules Docket No. 97-CE-79-AD, Room 1558, 601 E. 12th Street, Kansas
City, Missouri 64106.
Discussion
AD 87-18-09, Amendment 39-5725, currently requires inspecting (one-
time) the sides of the front and rear wood spars for compression cracks
on ACAC Model 8GCBC airplanes, repairing or replacing any wood spar
with compression cracks, and re-inspecting immediately after any
incident involving wing damage. AD 87-18-09 was the result of three
accidents involving ACAC Model 8GCBC airplanes where structural damage
to the wing caused by compression cracks in a wood spar was considered
to be a primary factor of the accidents.
Wood compression cracks are failures of wood fibers on a plane
perpendicular to the wood fiber longitudinal axis. Repetitive high
stress can initiate these compression cracks on the top surface of the
wing spar that is adjacent to doubler plate glue lines and rib nail
holes. These high stress conditions can occur during crop dusting,
banner and glider tow operations, turbulence, and rough field or float
operations. Compression cracks can also initiate if the wing contacts
the ground. Compression cracks can initiate at either the top or bottom
surface of the spar depending on the loads (either upward or downward)
at impact.
In-flight structural failure of the wing recently occurred on an
ACAC Model 8GCBC airplane that was initially inspected as required by
AD 87-18-09. A possible contributing factor of this incident was an
undetected compression crack on the right wing front spar.
Investigation of this accident and data acquired from inspections
of several ACAC Model 8GCBC airplanes indicate that wood spar
compression cracks can occur without previous wing damage. The data
indicates that detection of compression crack initiation is unlikely on
the sides of the spar, unless the crack is in an advanced state of
propagation. Based on this data, the FAA believes that repetitive
inspections are necessary. The FAA recently issued an NPRM on the Model
8GCBC airplanes that was published in the Federal Register on September
26, 1997 (62 FR 50527). This NPRM proposes to supersede AD 87-18-09,
and, if issued as a final rule, would require similar action to that
proposed in this document.
Reasons for the Proposed AD
The above-referenced incidents on the ACAC Model 8GCBC airplanes
prompted the FAA to review the service history of the other ACAC 8
series airplanes, as well as the 7 and 11 series airplanes. The FAA has
record of eight reports of accidents (five fatal) on ACAC 7 and 8
series airplanes, other than the Model 8GCBC airplanes. Four of these
accidents are attributed to overstress, two to wing failure due to
previous damage going undetected, one to an overload condition with
evidence of wing panel failure prior to impact, and one spar with an
out-of-specification wood spar grain slope. This review revealed 16
reports of spar crack damage (spar butt end and/or longitudinal
cracks), 6 reports of compression cracked spars, and 13 reports of
loose/missing rib nails. These reports break down as follows:
--Model 7AC (2,626 U.S. registered airplanes): 12 reports of spar crack
damage, plus 2 reports of loose/missing rib nails;
--Model 7BCM (253 U.S. registered airplanes): 1 report of spar crack
damage;
--Model 7ECA (871 U.S. registered airplanes): 1 report of a compression
cracked spar, plus 6 reports of loose/missing rib nails;
--Model 7GCBC (829 U.S. registered airplanes): 1 report of a
compression cracked spar;
--Model 7KCAB (482 U.S. registered airplanes): 2 reports of spar crack
damage, 2 reports of compression cracked spars, and 3 reports of loose/
missing rib nails; and
--Model 8KCAB (480 U.S. registered airplanes): 1 report of spar crack
damage, 2 reports of compression cracked spars, and 2 reports of loose/
missing rib nails.
The FAA believes that many cracked/damaged spars are not reported
because general aviation operators (operating in accordance with part
91 of the Federal Aviation Regulations (14 CFR part 91)) are not
required to submit service difficulty reports.
Relevant Service Information
The FAA has reviewed and approved the technical contents of ACAC
Service Letter 406, dated March 28, 1994, and ACAC Service Letter 417,
Revision A, dated October 2, 1997. ACAC Service Letter 406, dated March
28, 1994, includes procedures for conducting a detailed visual
inspection of both the front and rear wood wing spars for cracks;
compression cracks; longitudinal cracks through the bolt holes or nail
holes; and loose or missing rib nails (referred to as damage
hereafter). ACAC Service Letter 417, Revision A, dated October 2, 1997,
includes procedures for installing inspection holes and surface covers
and assuring that all applicable lower surface drain holes are
installed.
The FAA's Determination
After examining the circumstances and reviewing all available
information related to the incidents and accidents described above,
including the referenced service information, the FAA has determined
that (1) the wing design of all 7, 8, and 11 series airplanes equipped
with wood spars is similar and is conducive to spar cracks/damage; and
(2) AD action should be taken to prevent possible compression cracks
and other damage in the wood spar wing, which, if not detected and
corrected, could eventually result in in-flight structural failure of
the wing with consequent loss of the airplane.
Explanation of the Provisions of the Proposed AD
Since an unsafe condition has been identified that is likely to
exist or develop in other ACAC 7, 8, and 11 series airplanes (excluding
the Model 8GCBC airplanes) of the same type design, the FAA is
proposing AD action. The proposed AD would require installing
inspection holes on the top
[[Page 59312]]
and bottom wing surfaces, repetitively inspecting the front and rear
wood spars for damage, repairing or replacing any damaged wood spar,
and installing surface covers. Accomplishment of the proposed actions
would be as follows:
--Installations: in accordance with ACAC Service Letter 417, Revision
A, dated October 2, 1997;
--Inspections: in accordance with ACAC Service Letter 406, dated March
28, 1994; and
--Spar Repair and Replacement, as applicable: in accordance with
Advisory Circular (AC) 43-13-1A, Acceptable Methods, Techniques and
Practices; or other data that the FAA has approved for spar repair and
replacement.
Differences Between This Proposed AD and ACAC Service Letter 406
ACAC Service Letter 406, dated March 28, 1994, specifies the same
inspections as are proposed in this notice of proposed rulemaking
(NPRM). The differences between the service letter and NPRM are:
--the service letter specifies the proposed action within the next 30
days or 10 flight hours and at each 100 hour/annual inspection
thereafter. The FAA has determined that a more realistic and
enforceable compliance time would be to require:
1. The proposed initial inspection at the first annual
inspection that occurs 3 calendar months or more after the effective
date of the AD or within 15 calendar months after the effective date
of the AD, whichever occurs first; and
2. The proposed repetitive inspections thereafter at intervals
not to exceed 12 calendar months or 500 hours time-in-service (TIS),
whichever occurs first;
and
--the service letter applies to all ACAC 7 and 8 series airplanes,
whereas the NPRM applies to ACAC 7, 8, and 11 series airplanes with
similar design, except for the Model 8GCBC airplanes. The FAA
previously proposed similar AD action for the ACAC Model 8GCBC
airplanes, Docket No. 97-CE-33-AD (62 FR 50527, September 26, 1997).
Compliance Time of the Proposed AD
The compliance time of the proposed AD is presented in calendar
time and hours TIS. Although the unsafe condition specified in the
proposed AD is a result of airplane operation, operators of the
affected airplanes utilize their airplanes in different ways.
For example, an operator may utilize his/her airplane 50 hours TIS
in a year while utilizing the aircraft in no or very little crop
dusting operations, banner and glider tow operations, or rough field or
float operations. This airplane would obviously have a lower crack
propagation rate than an airplane operated 300 hours TIS a year in
frequent crop dusting operations, banner and glider tow operations, or
rough field or float operations. However, this airplane could have pre-
existing and undetected wood spar damage that occurred during previous
operations. In this situation, the damage to the wood spar would
propagate at a level that depends on the operational exposure of the
airplane and severity of the initial wood spar damage.
To assure that compression cracks do not go undetected in the wood
spars of the affected airplanes, the FAA has determined that the
following compliance times should be used:
1. The proposed initial inspection at the first annual
inspection that occurs 3 calendar months or more after the effective
date of the AD or within 15 calendar months after the effective date
of the AD, whichever occurs first; and
2. The proposed repetitive inspections thereafter at intervals
not to exceed 12 calendar months or 500 hours TIS, whichever occurs
first.
Cost Impact
The FAA estimates that 6,440 airplanes in the U.S. registry would
be affected by the proposed AD, that it would take approximately 6
workhours (Installations: 5 workhours; Initial Inspection: 1 workhour)
per airplane to accomplish the proposed action, and that the average
labor rate is approximately $60 an hour. Parts cost approximately $292
per airplane, provided that each airplane would only need 11 additional
standard inspection hole covers per wing bottom surface (total of 22
new covers per airplane). If the airplane would require the
installation of more inspection covers (i.e., a result of previous non-
factory wing recover work), the cost could be slightly higher. Based on
these figures, the total cost impact of the proposed AD on U.S.
operators is estimated to be $4,198,880 or $652 per airplane.
This cost figure is based on the presumption that no affected
airplane owner/operator has accomplished the installations or the
initial inspection. The FAA has no knowledge of any owner/operator of
the affected airplanes that has already accomplished the installations
and initial inspection.
This cost figure also does not account for repetitive inspections.
The FAA has no way of determining the number of repetitive inspections
each owner/operator of the affected airplanes will incur over the life
of his/her airplane. However, each proposed repetitive inspection would
cost substantially less than the initial inspection because of the cost
of the initial proposed inspection hole and cover installations would
not be repetitive. The inspection covers allow easy access for the
inspection of the wood spars, and the proposed compliance time would
enable the owners/operators of the affected airplanes to accomplish the
repetitive inspections at regularly scheduled annual inspections.
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 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) 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 has been placed 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 14
CFR part 39 of the Federal Aviation Regulations 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.
[[Page 59313]]
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
(AD) to read as follows:
American Champion Aircraft Company: Docket No. 97-CE-79-AD.
Applicability: The following airplane models, all serial
numbers, certificated in any category, that are equipped with wood
wing spars:
7AC
7BCM (L-16A)
7DC
S7EC
7GC
7GCB
7HC
7KCAB
S11AC
7ACA
7CCM (L-16B)
S7DC
7ECA
7GCA
7GCBA
7JC
8KCAB
11BC
S7AC
S7CCM
7EC
7FC
7GCAA
7GCBC
7KC
11AC
S11BC
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, repaired, or reconfigured in the area subject to
the requirements of this AD. For airplanes that have been modified,
altered, repaired, or reconfigured 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 in the body of this AD, unless
already accomplished.
To prevent possible compression cracks and other damage in the wood
spar wing, which, if not detected and corrected, could eventually
result in in-flight structural failure of the wing with consequent loss
of the airplane, accomplish the following:
(a) At the first annual inspection that occurs 3 calendar months or
more after the effective date of this AD or within the next 15 calendar
months after the effective date of this AD, whichever occurs first,
accomplish the following:
(1) Install inspection holes in the top and bottom surface of each
wing in accordance with American Champion Aircraft Corporation (ACAC)
Service Letter 417, Revision A, dated October 2, 1997. Assure that all
drainage holes are installed as depicted in this service letter, and
install drainage holes as necessary.
(2) Inspect (detailed visual) both the front and rear wood wing
spars for cracks; compression cracks; longitudinal cracks through the
bolt holes or nail holes; and loose or missing rib nails (referred to
as damage hereafter). Accomplish these inspections in accordance with
ACAC Service Letter 406, dated March 28, 1994.
(3) If any spar damage is found, prior to further flight,
accomplish the following:
(i) Repair or replace the wood wing spar in accordance with
Advisory Circular (AC) 43-13-1A, Acceptable Methods, Techniques and
Practices; or other data that is approved by the FAA for wing spar
repair or replacement.
(ii) If the wing is recovered, accomplish the installations
required by paragraph (a)(1) of this AD, as applicable.
(4) Install inspection hole covers on the top and bottom surface of
the wing in accordance with ACAC Service Letter 417, Revision A, dated
October 2, 1997.
(b) Within 12 calendar months or 500 hours TIS (whichever occurs
first) after accomplishing all actions required by paragraph (a) of
this AD, and thereafter at intervals not to exceed 12 calendar months
or 500 hours TIS, whichever occurs first, accomplish the inspection,
repair, replacement, and installation required by paragraphs (a)(2),
(a)(3), as applicable; including its subparagraphs; and (a)(4) of this
AD.
(c) If, after the effective date of this AD, any of the affected
airplanes are involved in an incident/accident that involves wing
contact damage (e.g., surface deformations such as abrasions, gouges,
scratches, or dents, etc.), prior to further flight after that
incident/accident, accomplish the inspection, repair, replacement, and
installation required by paragraphs (a)(2), (a)(3), as applicable;
including its subparagraphs; and (a)(4) of this AD.
(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.
(e) An alternative method of compliance or adjustment of the
initial or repetitive compliance time that provides an equivalent level
of safety may be approved by the Manager, Chicago Aircraft
Certification Office (ACO), 2300 E. Devon Avenue, Des Plaines, Illinois
60018. The request shall be forwarded through an appropriate FAA
Maintenance Inspector, who may add comments and then send it to the
Manager, Chicago ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Chicago ACO.
(f) All persons affected by this directive may obtain copies of the
documents referred to herein upon request to American Champion Aircraft
Corporation, P.O. Box 37, 32032 Washington Avenue, Highway D,
Rochester, Wisconsin 53167; or may examine these documents at the FAA,
Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th
Street, Kansas City, Missouri 64106.
Issued in Kansas City, Missouri, on October 27, 1997.
Mary Ellen A. Schutt,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-28984 Filed 10-31-97; 8:45 am]
BILLING CODE 4910-13-U
