[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