[Federal Register Volume 65, Number 189 (Thursday, September 28, 2000)]
[Notices]
[Pages 58307-58311]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24934]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Policy Statement Number ACE-00-23.561-01]


Issuance of Policy Statement, Methods of Approval of Retrofit 
Shoulder Harness Installation in Small Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of policy statement.

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SUMMARY: This document announces an FAA general statement of policy 
applicable to modifying small airplanes. This document advises the 
public, in particular, small airplane owners and modifiers, of more 
information related to acceptable methods of approval of retrofit 
harness installations. This notice is necessary to tell the public of 
FAA policy.

FOR FURTHER INFORMATION CONTACT: Michael Reyer, Federal Aviation 
Administration, Small Airplane Directorate, ACE-111, Room 301, 901 
Locust, Kansas City, Missouri 64106; telephone (816) 329-4131; fax 816-
329-4090; e-mail: <a href="/cdn-cgi/l/email-protection#335e5a505b52565f1d41564a5641735552521d545c45"><span class="__cf_email__" data-cfemail="e18c88828980848dcf9384988493a1878080cf868e97">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Background

    This notice announces the following policy statement, ACE-00-
23.561-01. The purpose of this statement is to address methods of 
approval for retrofit shoulder harness installations in small 
airplanes.

What Is the General Effect of This Policy?

    The FAA is presenting this information as a set of guidelines 
suitable for use. However, we do not intend that this policy set up a 
binding norm; it does not form a new regulation and the FAA would not 
apply or rely on it as a regulation.
    The FAA Aircraft Certification Offices (ACO's) and Flight Standards 
District Offices (FSDO's) that certify changes in type design and 
approve alterations in normal, utility, and acrobatic category 
airplanes should try to follow this policy when appropriate. Applicants 
should expect the certificating officials would consider this 
information when making findings of compliance relevant to retrofit 
shoulder harness installations.
    As with all advisory material, this statement of policy identifies 
one way, but not the only way, of compliance.

General Statement of Policy

Summary

    A retrofit shoulder harness installation in a small airplane may 
receive approval by Supplemental Type Certificate (STC), Field 
Approval, or as a minor change. An STC is the most rigorous means of 
approval and offers the highest assurance the installation meets all 
the airworthiness regulations. A Field Approval is a suitable method of 
approval for a shoulder harness installation that needs little or no 
engineering. Shoulder harness installations may receive approval as a 
minor change in certain cases. In such cases, the FAA certificated 
mechanic who installs the shoulder harness records it as a minor change 
by making an entry in the maintenance log of the airplane.
    The FAA does not encourage the approval of retrofit shoulder 
harness installations as minor changes. The preferred methods of 
approval are Supplemental Type Certificate or Field Approval. However, 
the FAA should not forbid the approval of a retrofit shoulder harness 
installation as a minor change in:
    <bullet> The front seats of those small airplanes manufactured 
before July 19, 1978, and
    <bullet> In other seats of those small airplanes manufactured 
before December 13, 1986.
    A retrofit shoulder harness installation may receive approval as a 
minor change in these small airplanes if:
    <bullet> The installation requires no change of the structure (such 
as welding or drilling holes).
    <bullet> The certification basis of the airplane is 14 CFR part 23 
before Amendment 23-20, part 3 of the Civil Air Regulations, or a 
predecessor regulation.
    In addition, a minor change installation should follow the guidance 
for hardware, restraint angles, and attachment locations provided in:
    <bullet> Advisory Circular (AC) 43.13-2A, Acceptable Methods, 
Techniques, and Practices Aircraft Alterations.
    <bullet> AC 21-34, Shoulder Harness--Safety Installations.
    <bullet> AC 23-4, Static Strength Substantiation of Attachment 
Points for Occupant Restraint System Installations.
    Installations approved as a minor change may not provide the 
occupant with the protection required by regulation (Civil Air 
Regulation (CAR) 3.386 or 14 CFR part 23, 23.561). However, a properly 
installed retrofit shoulder harness installation is a safety 
improvement over occupant restraint by seat belt alone.

Introduction

    In January 1997, the Anchorage Aircraft Certification Office (ACO) 
Manager requested the Small Airplane Directorate to study the issue of 
retrofit shoulder harness installations in small airplanes. The 
Anchorage ACO specifically requested guidance for a Supplemental Type 
Certificate (STC) project to install shoulder harness in Piper PA-18 
series airplanes. Shoulder harnesses are approved under Technical 
Standard Order (TSO)-C114 Torso Restraint Systems, or by other 
acceptable means appropriate to the certification basis of the airplane 
in which they will be installed. This policy statement addresses the 
approval of the shoulder harness installation only.
    During 1998, the Small Airplane Directorate took part in the 
Aviation Safety Program to increase the use and effectiveness of 
occupant restraint systems in general aviation airplanes. This program 
supports the occupant survivability element of the Administrator's 
Safety Agenda for general aviation. The FAA has a goal of significantly 
reducing the number of fatal accidents over a ten-year period.

[[Page 58308]]

Most of the content of this policy was presented in a paper at the 
August 19, 1998, meeting of this Aviation Safety Program.
    The Manager of the Aircraft Maintenance Division of Flight 
Standards, AFS-300, has reviewed and agrees with this policy.

General Discussion of Comments

Has FAA Taken Any Action to This Point?

    We issued a notice of policy statement, request for comments. This 
proposed policy appeared in the Federal Register on June 14, 2000 (65 
FR 37449) and the public comment period closed July 14, 2000.

Was the Public Invited To Comment?

    The FAA encouraged interested people to join in making this 
proposed policy. We received comments from 12 different commenters. 
Commenters included pilots, operators, individuals, manufacturers, and 
organizations representing these groups. Most of the commenters were 
supportive of the proposed policy.
    Commenters praised the proposed policy for promoting safety, 
especially on older airplanes. We will discuss the general comments and 
concerns then we will discuss comments that are more specific.

General and Miscellaneous Comments

    One individual wrote, ``I would like to give my support to the 
opportunity for minor changes to allow shoulder harness installations 
in older aircraft.'' Another commenter noted, ``This is indicative of a 
long overdue recognition that better is the enemy of the good, and 
people need to make these reasonable improvements even if they cannot 
be of the standard of current regulations for new aircraft. Well 
done!'' A commenter representing an organization wrote that they had 
reviewed the policy memorandum proposal on retrofit shoulder harness on 
small airplanes and agree.

Mandatory Harness Requirement

    A pilot wrote, ``Having actually been in an aircraft crash 
situation, I feel quite strongly that shoulder harnesses in all 
aircraft seating positions should be mandatory.''
    Removing many of the barriers associated with installing retrofit 
shoulder harnesses will allow owners of older aircraft to have them 
installed in their aircraft. With the removal of these barriers, it is 
not necessary to place an additional regulatory burden on aircraft 
owners. The policy statement does not form a new regulation and the FAA 
will not apply or rely on it as a regulation.

Acceptable Harness for Minor Change Installations

    An operator and pilot commented, ``Many of the racing industries 
commonly available four and five point safety harnesses are tested to 
standards and loads that easily exceed the FAA's 1,500 pound failure 
limit load. These very affordable harnesses, much less expensive 
shoulder and lap harnesses could be easily installed with over the 
counter hardware aviation hardware and would be a highly positive 
safety enhancement.'' Similarly, a manufacturer wrote that minor change 
installations of retrofit shoulder harnesses should include those 
produced under a Parts Manufacturer Approval (PMA), harnesses that meet 
military specification requirements, and harnesses that meet Society of 
Automotive Engineers aircraft restraint system requirements.
    We agree that removing many of the barriers associated with the 
installation of retrofit shoulder harnesses will allow owners of 
certain small aircraft to increase the level of safety in their 
aircraft. We also agree that we should allow minor change installations 
that use non-TSO-C114 harnesses. However, apart from TSO-C114 
harnesses, we will accept only those harnesses that meet the Society of 
Automotive Engineers Aerospace Standard 8043, harnesses produced under 
a Parts Manufacturer Approval (PMA) or harnesses that meet aircraft 
military specification requirements. We have revised the policy 
statement to include these other harnesses.

Attachments to Unsupported Tubes

    The same manufacturer also suggested that:
    <bullet> FAA allow attachments to unsupported tube elements as 
minor changes;
    <bullet> The unsupported tube issue needs more study;
    <bullet> Companion guidance materiel to the retrofit shoulder 
harness policy statement should address restraint attachment points; 
and
    <bullet> FAA develop guidance regarding replacement and maintenance 
of existing seat belts and shoulder harness installations.
    We disagree. The FAA will study this suggestion in further detail 
but we are unwilling to change existing guidance on methods of 
attachment. We agree that we should develop companion guidance that 
addresses the restraint points and replacement and maintenance.

Level of Safety, Attachment Methods, and Material Variability

    A second manufacturer wrote concerning the policy that we address:
    <bullet> Appropriate attachment methods in the policy,
    <bullet> Production material variability, and
    <bullet> Improper installation and attachment.
    We agree with these comments and address them in the policy 
statement.
    This manufacturer also wants to see the policy address the loading, 
level of safety, head impact injury criteria, and strength requirements 
of 14 CFR part 23, Sec. 23.561.
    The FAA disagrees. Installation of shoulder harnesses may be 
accomplished without FAA approval if the installation is a minor change 
to the airplane design. If the installation is a major change, a 
Supplemental Type Certificate or Field Approval must be obtained.
    For aircraft type certificated before the effective date of 
Amendment 23-20, the shoulder harnesses need not meet the requirements 
of 14 CFR 23.561, and its predecessor regulations, if the installation 
of the harness is not essential to the operation of the airplane. A 
shoulder harness installed as a minor change does not have to provide 
the level of safety required in 14 CFR 23.561. The head impact injury 
criteria and strength requirements of the harnesses, including fitting 
factors, do not have to be met for minor change installations.

The Policy

References

    1. Advisory Circular (AC) 21-34, Shoulder Harness--Safety Belt 
Installations, June 4, 1993.
    2. AC 23-4, Static Strength Substantiation of Attachment Points for 
Occupant Restraint System Installations, June 20, 1986.
    3. AC 43.13-2A, Acceptable Methods, Techniques, and Practices--
Aircraft Alternations, Revised 1977.
    4. Order 8300.10, Airworthiness Inspector's Handbook, Change 12, 
December 14, 1999, Volume II.
    5. Technical Standard Order (TSO)-C114, Torso Restraint Systems, 
March 27, 1987.
    6. Technical Standard Order C-22f, Safety Belts, May 1, 1972.

Discussion

What Are the Requirements?

    1. Front seat shoulder harnesses required. Section 23.785 of 14 CFR 
part 23 as amended by Amendment 23-19 effective July 18, 1977, required 
all normal, utility, and acrobatic category

[[Page 58309]]

airplanes for which application for type certificate was made on or 
after July 18, 1977, to have an approved shoulder harness for each 
front seat. Section 91.205(b)(14) requires all small civil airplanes 
manufactured after July 18, 1978, to have an approved shoulder harness 
for each front seat. The shoulder must be designed to protect the 
occupant from serious head injury when the occupant experiences the 
ultimate inertia forces specified in Sec. 23.561(b)(2). The inertia 
force requirements are discussed in paragraph 3 below.
    2. Shoulder harnesses required at all seats. Section 91.205(b)(16) 
requires all normal, utility, and acrobatic category airplanes with a 
seating configuration of 9 or less, excluding pilot seats, manufactured 
after December 12, 1986, to have a shoulder harness, for forward-facing 
and aft-facing seats, that meets the requirements of Sec. 23.785(g) 
[which requires that the occupant be protected from the ultimate 
inertia forces specified in Sec. 23.561(b)(2)]. Section 23.785(g) also 
provides: ``For other seat orientations, the seat and restraint means 
must be designed to provide a level of occupant protection equivalent 
to that provided for forward and aft-facing seats with safety belts and 
shoulder harnesses installed.'' The above part 91 operating rule stems 
from Sec. 23.2, Special retroactive requirements, Amendment 23-32, 
effective December 12, 1985.
    3. Belts or harnesses provided for in the design. Civil Air 
Regulation (CAR) 3.386 and part 23, Sec. 23.561, Amendments 23-0 
through 23-34, effective February 17, 1987, require occupant protection 
from serious injury during a minor crash landing when ``proper use is 
made of belts or harnesses provided for in the design,'' when the 
occupants are subjected to the following ultimate inertia forces:

------------------------------------------------------------------------
                                    Normal & utility       Acrobatic
                                        category            category
------------------------------------------------------------------------
Forward..........................  9.0g                9.0g
Sideward.........................  1.5g                1.5g
Upward...........................  3.0g                4.5g
------------------------------------------------------------------------

    With Amendment 23-36, effective September 14, 1998, the text of 
Sec. 23.561 quoted above was changed to read: ``proper use is made of 
seats, safety belts, and shoulder harnesses provided for in the 
design.'' Section 23.785(b) was also changed to read:
    ``Each forward-facing or aft-facing seat/restraint system in 
normal, utility, or acrobatic category airplanes must consist of a 
seat, safety belt, and shoulder harness that are designed to provide 
the occupant protection provisions required in Sec. 23.562 of this 
part. Other seat orientations must provide the same level of occupant 
protection as a forward-facing or aft-facing seat with a safety belt 
and shoulder harness, and provide the protection provisions Sec. 23.562 
of this part.''
    The emergency landing ultimate inertia load factors have remained 
unchanged from Amendment 23-36 through Amendment 23-52, effective April 
30, 1997. Amendment 23-52 is the latest amendment level to part 23.
    For inertia force requirements for occupant protection preceding 
CAR 3, refer to Table 1 in AC 21-34 which lists the requirements for 
the regulations dating from Bulletin 7-A to the original part 23.

What Are the Methods of Approval for Retrofit Shoulder Harness 
installations?

    1. Supplemental Type Certificate (STC). An STC is the most 
desirable and most rigorous approval. The STC offers the highest 
assurance that all of the airworthiness regulations have been met. The 
STC approvals are issued by the FAA Aircraft Certification Offices 
(ACOs). STC approvals are usually obtained by a shoulder harness 
installation kit supplier for multiple airplane installations in an 
airplane model or model series.
    AC's 21-34 and 23-4 (References 1 and 2) provide guidance and 
acceptable means of compliance for shoulder harness and seat belt 
installations. AC 23-4 specifically addresses part 23 installations. 
These AC's are also applicable to installations in airplanes having a 
certification basis of predecessor regulations (for example, CAR 3).
    An applicant for an STC may use a salvaged airplane fuselage to 
substantiate the strength of the fuselage and the shoulder harness 
attachment fittings by structural tests, since the shoulder harness 
attachment structural test may damage an airworthy fuselage. It may be 
problem that the available test airframe may be stronger than the 
lowest strength production airframe. This may be a problem in steel 
tube airframes.
    During many years of producing such airframes, various 
specification materials may have been used. For example, many CAR 3 
(and predecessor regulations) airplanes were originally produced from 
1025 steel tubing and later constructed from higher strength 4130 
steel. In one case studied, two different specification 1025 steel 
tubings were used which may have an ultimate tensile strength (UTS) 
ranging from 55,000 to 79,000 pounds per square inch (psi). The UTS for 
4130 steel is 90,000 to 95,000 psi.
    The test article should be representative of the lowest strength 
production airframe. This may be accomplished by a conformity 
inspection using the production drawings. The strength of materials of 
parts affected by the modification needs to be verified by the airframe 
manufacturer's process and production records. The serial number of the 
test article needs to be verified.
    An alternative course of action would be to determine, by 
appropriate tests (for example, chemical analysis, hardness tests, 
strength tests), the strength of the parts of the test article affected 
by the modification. Follow with testing to a conservatively higher 
load that accounts for the difference in strengths of the test article 
and the lowest strength production article. Determination of the higher 
applied test load should take into account any uncertainty in the 
test(s) used to determine the strength of the material.
    Another alternative course of action may be to conduct the harness 
pull test on the available test airframe. The applicant may then 
substantiate the strength of other tubing specifications by a 
combination of test results and analysis.
    AC 23-4 provides an acceptable means of compliance for static 
strength substantiation of attachment points for occupant restraint 
system installations. A test block is described to apply the 9.0-g 
forward inertia load. The safety belt installation alone is tested to 
100 percent of the load. The shoulder and safety belt combined load is 
distributed 40 percent to the shoulder harness and 60 percent to the 
seat belt.
    In airplanes having side-by-side seats, the pull test may need to 
be applied simultaneously to the harness fittings for both seats. 
However, this depends on the type of harness and where the upper ends 
are anchored. Normally, this would not be necessary for a single 
diagonal belt shoulder harness attached to the outboard fuselage side 
or wing spar root end.
    In the case of a pull test for a retrofit shoulder harness 
installation in the tandem seated tubular steel PA-18 fuselage, the 
forward inertia load was applied simultaneously for both harnesses. 
This was done for convenience in applying and reacting the loads. It 
was found, that due to the tube geometry, the load at the aft harness 
attachment caused a tension in the rear spar carrythrough tube. The 
front seat shoulder harness upper end was attached to the rear spar 
carrythrough tube. This enabled the

[[Page 58310]]

front seat harness attachment to test to a higher load than if the pull 
test was done to each harness individually. In such a case, the test 
loads for each harness should be done individually.
    Part 21, Sec. 21.50(b) requires the holder of an STC to furnish 
Instructions for Continued Airworthiness, prepared in accordance with 
Sec. 23.1529.
    An STC can not be used to modify an aircraft without the permission 
of the STC holder. FAA Notice 8110.69 dated June 30, 1997, requires the 
STC holder to provide the customer (installer or airplane owner) with a 
signed permission statement that includes the following:
    <bullet> Product (aircraft, engine, propeller, or appliance) to be 
altered, including serial number of the product;
    <bullet> The STC number; and
    <bullet> The person(s) who is being given consent to use the STC.
    The permission statement needs to be kept as part of the aircraft 
records. The requirement for this permission statement originated in 
the Federal Aviation Authorization Act of 1996 (Public Law 104-264). 
This provision was put into law to try to stop the pirating of STC's.
    2. Field Approval. A shoulder harness installation in a small 
airplane may receive a Field Approval (FAA Form 337) granted by a 
Flight Standards Aviation Safety Inspector. Field Approvals are 
appropriate for alterations that involve little or no engineering. If 
the installation requires structural modifications, an Aircraft 
Certification Office will need to assist in the Field Approval process 
by approving the structural aspects of the installation. A Field 
Approval constitutes a change to type design and must meet the same 
regulatory requirements as an STC.
    AC 43.13-2A (Reference 3) contains methods, techniques, and 
practices acceptable to the Administrator for use in altering civil 
aircraft. Chapter 9 covers shoulder harness installations. Section 3 
covers attachment methods. Shoulder harnesses installed under Field 
Approval must meet the same regulatory requirements as an STC. 
Therefore, the applicant should demonstrate by test 9.0-g forward load 
capability. The test load should be 814 pounds for Normal Category or 
910 pounds for Utility or Acrobatic Category, in accordance with AC 23-
4.
    Reference 4, Chapter 1, Perform Field Approval of Major Repairs and 
Major Alterations, Section 1, paragraph 5.D(2) states: ``Acceptable 
data that may be used on an individual basis to obtain approval are:
    <bullet> AC's 43.13-1A and 43.13-2A, as amended*
    <bullet> Manufacturer's technical information (for example, 
manuals, bulletins, kits, and so on)
    <bullet> FAA Field Approvals''

    * Note: Advisory Circular (AC) 43.13-1B, dated September 8, 1998 
superseded AC 43.13-1A.

    When using a previous Field Approval as acceptable data, the pull 
test need not be done if it can be determined that a previous pull test 
applied 814 pounds for Normal Category or 910 pounds for Utility or 
Acrobatic Category. Field Approvals for shoulder harness installations 
should not be done by referencing a previous Field Approval and 
deleting the pull test, unless the attachment parts have a Parts 
Manufacturer Approval (PMA), or other FAA approval. If the attachment 
parts have no FAA approval, the strength is not known or assured, since 
they have not been manufactured to an FAA approved quality control 
system.
    Shoulder harness installations attaching to the center of an 
unsupported wing carrythrough tube, or other unsupported member, should 
not receive a Field Approval without a design approval from an Aircraft 
Certification Office. Applying the test load in such cases may cause 
damage or permanent set to the affected structure.
    Existing FAA guidance, including AC 43.13-2A and AC 21-34, 
recommend against attachment to the center of unsupported members. 
Figure 9-16 in AC 43.13-2A shows typical shoulder harness attachments 
to tubular members. These are all at tube intersections and not at the 
center of unsupported tubes.
    Figure 9-12 shows a typical wing carrythrough member installation. 
This appears to be in the center of the carrythrough member that is a 
hat section as found in metal skinned airplanes. Part of the figure 
shows that the hat section is riveted to sheet metal skin (which would 
provide longitudinal support).
    Personnel performing the Field Approval must ensure that both the 
harness and belt are compatible and have a TSO approval.
    Flight Standards Information Bulletin for Airworthiness (FSAW) 98-
03, dated January 30, 1998, (Reference 4) requires that a Field 
Approval include Instructions for Continued Airworthiness prepared (in 
the case of part 23 airplanes) under Sec. 23.1529. The Instructions 
will be documented on FAA Form 337, and become a part of either the 
inspection or maintenance program of the aircraft, or both.
    3. Minor change. Part 21 Sec. 21.93(a), Classification of changes 
in type design, states: ``A minor changes is one that has no 
appreciable effect on the weight, balance, structural strength, 
reliability, operational characteristics, or other characteristics 
affecting the airworthiness of the product.''
    Information provided to us by the Anchorage ACO indicates that some 
shoulder harness installations, that provide known safety improvements, 
have been approved as a minor change. In these situations, the FAA 
certificated mechanic who installs it makes an entry in the maintenance 
log of the airplane.
    One shoulder harness installation kit supplier uses this process 
(no FAA approvals) to install shoulder harnesses in PA-18 airplanes. 
The installation does not require modification of the airframe. The 
front seat harness attaches to the center of the rear wing spar 
carrythrough tube. However, it may not meet the 9.0-g forward inertia 
load required by CAR 3.386. The kit supplier stated that some airplane 
owners who had accidents reported that the harness installation had 
saved their lives.
    In general, shoulder harness installations should not use the 
center of an unsupported wing carrythrough tube or other unsupported 
member as an attachment point. This type of attachment may pose a risk 
to the structural integrity of the airplane. Although the attachment 
may be a clamp-on fitting that does not alter the existing airframe, 
the installation may result in a major change in the type design. This 
is because the shoulder harness attachment may introduce new loading 
conditions into the carrythrough tube.
    It is acceptable for the carrythrough structure to be damaged in an 
emergency landing. However, it is unacceptable for the tube to fail in-
flight. Carrythrough tubes, highly loaded in compression, may 
experience a beam-column buckling failure if the occupant applies a 
load to the shoulder harness attachment. In some cases, very small 
loads on the shoulder harness attachment may cause beam-column buckling 
failures.
    Some shoulder harnesses that have been installed by minor change do 
not have a TSO approval. TSO-C114, Torso Restraint Systems, was issued 
March 27, 1987. Torso restraint systems manufactured before that date 
did not have to meet the prescribed Society of Automotive Engineers 
standard, Aerospace Standard 8043, Aircraft Torso Restraint System, 
dated March 1986. AC 43.13-2A and AC 21-34 provide guidance for 
acceptable

[[Page 58311]]

harnesses. Acceptable harnesses for minor change installations include:
    <bullet> Harnesses that meet TSO-C114 or Military Specification 
(MIL-SPEC) requirements,
    <bullet> Harnesses that have been produced under a Parts 
Manufacturer Approval (PMA), or
    <bullet> Other harnesses appropriate to the certification basis of 
the aircraft.
    We have studied the circumstances and legality of shoulder harness 
installations done by minor change. An airplane owner may wish to 
install shoulder harnesses, but an STC or prior Field Approval is not 
available for his airplane. In this case, it is not likely that an 
individual airplane owner would apply for an STC or a Field Approval. 
This is because of the costs involved in hiring an engineering 
consultant to perform the structural test and any associated structural 
analysis. Also, there is a possibility that the airframe may be damaged 
during the pull test. In such installations, a pull test would not be 
done and there is no assurance that the installation will provide 
occupant protection to the ultimate inertia force requirements 
(particularly the 9.0-g forward force) of Sec. 23.561 or CAR 3.386.
    Concerning the legality of shoulder harness installation by minor 
change, we conclude: Since CAR 3.386 and Sec. 23.561(b)(1) before 
Amendment 23-36 (which became effective September 14, 1988) state that 
``proper use is made of belts or harnesses provided in the design,'' 
the previously approved seat belt installation alone must meet the 
prescribed ultimate inertia forces.
    Civil Air Regulation 3.652, Functional and installational 
requirements, states: ``Each item of equipment which is essential to 
the safe operation of the airplane shall be found by the Administrator 
to perform adequately the functions for which it is to be used, shall 
function properly when installed, and shall be adequately labeled as to 
its identification, function, operational limitations, or any 
combination of these, whichever is applicable.''
    Before Amendment 23-20 (which became effective September 1, 1977), 
Sec. 23.1301 contained essentially the same requirement as CAR 3.652. 
Amendment 23-20 deleted the words ``essential to safe operation'' and 
made the provisions of Sec. 23.1301 applicable to ``each item of 
installed equipment.''
    Regarding these rules we conclude that if a shoulder harness is not 
required equipment, it is not essential to the safe operation of the 
airplane. Therefore, CAR 3.652 and Sec. 23.1301, before Amendment 23-
20, should not be used as a basis to prohibit shoulder harness 
installation by minor change. These rules should be applied to shoulder 
harness installations made by STC and Field Approval.
    The mechanic making such installations should consult AC 43.13-2A, 
Chapter 9, for information on restraint systems, effective restraint 
angles, attachment methods, and other details of installation.

    Issued in Kansas City, Missouri, on September 19, 2000.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 00-24934 Filed 9-27-00; 8:45 am]
BILLING CODE 4910-13-M


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