Special Conditions: Boeing, Model 747-8 Series Airplanes; Door 1 Extendable Length Escape Slide, 26957-26959 [2011-11294]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 76, Number 90 (Tuesday, May 10, 2011)]
[Proposed Rules]
[Pages 26957-26959]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-11294]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM455; Notice No. 25-11-12-SC]


Special Conditions: Boeing, Model 747-8 Series Airplanes; Door 1 
Extendable Length Escape Slide

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Boeing Model 
747-8 airplane. This airplane will have a novel or unusual design 
feature(s) associated with an extendable length escape slide. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. These proposed 
special conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

DATES: We must receive your comments by May 31, 2011.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. NM455, 1601 Lind Avenue, SW., Renton, 
Washington, 98057-3356. You may deliver two copies to the Transport 
Airplane Directorate at the above address. You must mark your comments: 
Docket No. NM455. You can inspect comments in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Jayson Claar, FAA, Airframe and Cabin 
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue, SW., Renton, Washington, 
98057-3356; telephone (425) 227-2194; facsimile (425) 227-1232.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special conditions, explain the 
reason for any recommended change, and include supporting data. We ask 
that you send us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. You can inspect the docket before 
and after the comment closing date. If you wish to review the docket in 
person, go to the address in the ADDRESSES section of this preamble 
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions based on the comments we receive.
    If you want us to acknowledge receipt of your comments on this 
proposal, include with your comments a self-addressed, stamped postcard 
on which you have written the docket number. We will stamp the date on 
the postcard and mail it back to you.

Background

    On November 4, 2005, The Boeing Company applied for an amendment to 
Type Certificate Number A20WE to include the Model 747-8 series 
passenger airplane. The Model 747-8 is a derivative of the 747-400. The 
Model 747-8 is a four-engine jet transport airplane that will have a 
maximum takeoff weight of 975,000 pounds, new General Electric GEnx-
2B67 engines, and the capacity to carry 605 passengers.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Boeing must show that the Model 747-8 (hereafter referred 
as 747-8) meets the applicable provisions of part 25, as amended by 
Amendments 25-1 through 25-120 plus Amendment 25-127 for Sec.  
25.765(a), except for earlier amendments as agreed upon by the FAA. 
These regulations will be incorporated into Type Certificate No. A20WE 
after type certification approval of the 747-8.
    In addition, the certification basis includes other regulations, 
special conditions, and exemptions that are not relevant to these 
proposed special conditions. Type Certificate No. A20WE will be updated 
to include a complete description of the certification basis for these 
airplanes.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the 747-8 because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec.  21.16.

[[Page 26958]]

    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for the model be amended 
later to include any other model or series that incorporates the same 
design feature, or should any other model or series already included on 
the same type certificate be modified to incorporate the same or 
similar novel or unusual design feature, the special conditions would 
also apply to other model or series under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the 747-8 must comply with the fuel vent and exhaust 
emission requirements of 14 CFR part 34 and the noise certification 
requirements of 14 CFR part 36.
    Special conditions, as defined in Sec.  11.19, are issued under 
Sec.  11.38, and become part of the type certification basis under 
Sec.  21.101.

Novel or Unusual Design Features

    The Boeing Model 747-8 will incorporate the following novel or 
unusual design features: The 747-8 design offers seating capacity on 
two separate decks, the main deck with a maximum passenger capacity of 
495 and the upper deck with a maximum passenger capacity of 110. 
Section 25.810(a)(1)(iii) requires that after full deployment the 
emergency escape system assist means must be long enough so that the 
lower end is self-supporting on the ground and provides safe evacuation 
of occupants to the ground after collapse of one or more legs of the 
landing gear. Typically, airplanes have fixed-length slides that meet 
the above requirements. However, it was not possible to use fixed-
length slides for the 747-8 Door 1 because of the difference between 
normal sill height and the high-sill height associated with collapse of 
some of the landing gear in an emergency. Some combinations of landing 
gear collapse could cause the airplane to tip back on its tail. The 
747-8 Door 1 escape slide is an extendable length design to meet the 
gear collapse and tail tip conditions. The regulations do not 
adequately address the certification requirements for an extended 
length escape slide.

Discussion

    The regulations governing the certification of the 747-8 do not 
adequately address the certification requirements for an extendable 
length escape slide. The only reference to extendable length escape 
slides in Technical Standard Order (TSO) C69c, Emergency Evacuation 
Slides, Ramps, Ramp/Slides, and Slide/Rafts, is in the inflation time 
requirement section. The requirements of Sec.  25.801(a)(1)(iii) for 
other airplanes has been addressed by a single length escape slide. 
However, for the 747-8 Door 1, it was not possible to have a single 
length escape slide because of the extreme difference in sill heights 
between normal sill height and high-sill height associated with 
collapse of some of the landing gear, and the additional case of the 
airplane tipping back on its tail. For Door 1, the normal sill height 
is approximately 187 inches, and the high-sill height is approximately 
346 inches.
    The proposed design of the extendable length escape system has an 
approximately 12 foot long extension packed at the toe end of the 
escape slide. During normal operation, the extension portion remains 
packed at the toe end. The airplane is equipped with an electronic 
sensor that evaluates the attitude of the airplane, and determines if 
the extendable portion is needed. When the extended length is needed, 
the system sends a signal to an electronic sign on the door to indicate 
to the flight attendant that the extendable length of the slide needs 
to be inflated. The extendable length inflation system is activated by 
pulling on a separate inflation handle located on the right side of the 
slide girt.
    The Airbus A380 airplane has an extendable length slide and the FAA 
issued Special Conditions Number 25-323-SC to address the installation 
of the extendable length escape slide in that airplane. These 
previously issued special conditions provide a starting point for 
developing special conditions for the 747-8 airplane, which consider 
and evaluate the unique aspects of this airplane's design.
    The extension is intended only for use at high-sill heights. A 
typical fixed-length slide operating at high-sill height does not 
satisfy all of the performance requirements of Sec.  25.810, but its 
variations in performance are understood and largely predictable. 
Certain performance criteria are valid regardless of sill height, while 
other aspects of performance can be expected to decline at higher sill 
heights. With an extendable slide, there is a step change in 
configuration and potentially a change in performance. Therefore, 
special conditions are needed to ensure acceptable performance in the 
extended mode.
    Section 25.810 specifies the basic performance requirements for 
escape slides, including wind testing, repeatability testing, and 
testing at adverse sill heights. Section 25.1309(a) requires systems to 
perform under foreseeable operating conditions, such as extreme 
temperatures, and demonstrate that the system design is appropriate for 
its intended function. Standards for the equipment itself are in TSO-
C69c and contribute to a satisfactory installation.
    Typically, wind tests are only conducted on fixed-length slides at 
normal sill height. Since the regulations require that the escape 
slides have the capability of being deployed in 25-knot winds directed 
from the most critical angle, escape slides usually exceed 25 knot 
performance at other than the critical angle. The same is expected to 
be true of the slide in its extended mode, but some reduction in the 
required wind velocity is appropriate since the slide will be in an 
abnormal condition. Available data indicate that the capability of 
being deployed in 22-knot winds is appropriate to cover the slide in 
its extended mode at normal sill height. This corresponds to roughly 
75% of the wind energy required for the slide in its normal attitude 
and will ensure that the slide can function in its extended mode at 
least as well as a fixed-length slide under similar abnormal 
conditions.
    These special conditions also specify a rate for passenger 
evacuation that is consistent with that of fixed-length escape slides.

Applicability

    As discussed above, these special conditions are applicable to the 
Boeing Model 747-8 airplane. Should Boeing apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, the special conditions would 
apply to that model as well under the provisions of Sec.  21.101.
    Certification of the Boeing Model 747-8 is currently scheduled for 
November 2011. The substance of these special conditions has been 
subject to the notice and public-comment procedure in several prior 
instances. Therefore, because a delay would significantly affect both 
the applicant's installation of the system and certification of the 
airplane, we are shortening the public-comment period to 20 days.

Conclusion

    This action affects only certain novel or unusual design features 
of the Boeing Model 747-8 airplane. It is not a rule of general 
applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:


[[Page 26959]]


    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Boeing Model 747-8 airplanes.
    In addition to the provisions of 14 CFR part 25, the following 
special conditions are proposed:
    1. The extendable escape slide must receive TSO-C69c or latest TSO 
authorization published at the time of TSO application for the Door 1 
Slide.
    2. In addition to the requirements of Sec.  25.810(a)(1)(iii) for 
usability in conditions of landing gear collapse, the deployed escape 
slide in the extended mode must demonstrate an evacuation rate of 45 
persons per minute per lane at the sill height corresponding to 
activation of the extension.
    3. In lieu of the requirements of Sec.  25.810(a)(1)(iv), the 
escape slide with the extendable section activated must be capable of 
being deployed in 22-knot winds directed from the critical angle, with 
the airplane on all its landing gear, with the assistance of one person 
on the ground. Two deployment scenarios must be addressed as follows:
    (a) Extendable section is activated during the inflation time of 
the basic slide and,
    (b) Extendable section is activated after the basic slide is 
completely inflated.
    4. Pitch sensor tolerances and accuracy must be taken into account 
when demonstrating compliance with Sec.  25.1309(a) for the escape 
slide in both extended and unextended modes.
    5.(a) There must be a ``slide extension'' warning such that the 
cabin crew is immediately made aware of the need to deploy the 
extendable section of the slide. The ability to provide such a warning 
must be available for ten minutes after the airplane is immobilized on 
the ground.
    (b) There must be a positive means for the cabin crew to determine 
that the extendable portion of the slide has been fully erected.
    6. Whenever passengers are carried on the main deck of the 
airplane, there must be a cabin crewmember stationed on each side of 
the airplane located near each Door 1 Exit. This special condition must 
be included in the airplane flight manual as a limitation.

    Issued in Renton, Washington, on May 3, 2011.
KC Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-11294 Filed 5-9-11; 8:45 am]
BILLING CODE 4910-13-P