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Special Conditions: Gulfstream Model G150 Airplanes; Side-Facing Single-Occupant Seats

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Federal Aviation Administration (FAA), DOT.


Final special conditions; request for comments.


These special conditions are issued for Gulfstream Model G150 airplanes. These airplanes will have a novel or unusual design feature(s) associated with side-facing single-occupant seats. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These 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.


The effective date of these special conditions is August 9, 2005. Comments must be received on or before October 6, 2005.


Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attn: Rules Docket (ANM-113), Docket No. Start Printed Page 48843NM325, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. Comments must be marked: Docket No. NM325. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

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John A. Shelden, FAA, Airframe/Cabin Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone (425) 227-2785; facsimile (425) 227-1232.

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The FAA has determined that notice and opportunity for prior public comment hereon are impracticable because these procedures would significantly delay issuance of the approval design and thus delivery of the affected aircraft. In addition, the substance of these special conditions has been subject to the public comment process in several prior instances with no substantive comments received. The FAA therefore finds that good cause exists for making these special conditions effective upon issuance.

Comments Invited

Interested persons are invited to submit such written data, views, or arguments as they may desire. Communications should identify the rules docket number and be submitted in duplicate to the address specified above. The Administrator will consider all communications received on or before the closing date for comments. The special conditions may be changed in light of the comments received. All comments received will be available in the Rules Docket for examination by interested persons, both before and after the closing date for comments. A report summarizing each substantive public contact with FAA personnel concerning this rulemaking will be filed in the docket. Persons wishing the FAA to acknowledge receipt of their comments submitted in response to these special conditions must include with those comments a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. NM325.” The postcard will be date stamped and returned to the commenter.


On September 22, 2002, Gulfstream Aerospace LP (GALP), Ben Gurion Airport, Tel Aviv, Israel, applied for a type certificate for its new Model G150 airplane. The Gulfstream Model G150 is a twin-engine, pressurized executive jet airplane with standard seating provisions for 11 passenger/crew and allowance for baggage and optional equipment. This airplane will have a maximum takeoff weight of 26,000 pounds and will have two aft-mounted Honeywell TFE 731-40AR-200G engines.

Type Certification Basis

Under the provisions of 14 CFR 21.17, GALP must show that Gulfstream Model 150 airplanes meet the applicable provisions of part 25, effective February 1, 1965, as amended by Amendment 25-1 through Amendment 25-107.

If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR part 25) do not contain adequate or appropriate safety standards for Gulfstream Model 150 airplanes because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Gulfstream Model 150 airplanes 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; and the FAA must issue a finding of regulatory adequacy pursuant to section 611 of Public Law 92-574, the “Noise Control Act of 1972.”

Special conditions, as defined in § 11.19, are issued in accordance with § 11.38 and become part of the type certification basis in accordance with § 21.17(a)(2).

Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same novel or unusual design feature, the special conditions would also apply to the other model.

Novel or Unusual Design Features

Gulfstream Model G150 airplanes offer interior arrangements that include single-occupant side-facing seat installations. One arrangement includes an aft right-hand (RH) toilet installation, which will be approved for occupancy during taxi, takeoff, and landing. The belted toilet seat is a single-occupant side-facing seating system located in the aft, RH portion of the cabin. It consists of a toilet assembly, toilet cabinet, forward partition, contact pad, and restraint system (lap belt).

The existing regulations do not provide adequate or appropriate safety standards for occupants of side-facing seats. In order to provide a level of safety that is equivalent to that afforded occupants of forward- and aft-facing seats, additional airworthiness standards, in the form of special conditions, are necessary. These special conditions supplement part 25 and, more specifically, supplement §§ 25.562 and 25.785. The requirements contained in these special conditions consist of both test conditions and injury pass/fail criteria.


Section 25.785(b), “Seats, berths, safety belts, and harnesses,” requires that “each seat * * * at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§ 25.561 and 25.562.” Additionally, § 25.562, “Emergency landing dynamic conditions,” requires dynamic testing of all seats occupied during takeoff and landing. The relative forces and injury mechanisms affecting the occupants of side-facing seats during an emergency landing are different from those of standard forward- or aft-facing seats, or seats equipped with conventional restraint systems.

Side-facing Seats: Amendment 25-64, which adopted § 25.562, enhances occupant protection during emergency landing conditions. Although the rule was written with forward- and aft-facing seats in mind, the orientation of the seat does not change the relevant test conditions, and the rule applies to all seats regardless of orientation.

The dynamic test conditions included in § 25.562 are directly applicable to side-facing seats. However, for injury pass/fail criteria, the orientation of the seat may be significant. For forward-, aft-, and side-facing seats the injury criteria are currently limited to head, spine, and femur loads. The head and lumbar loads are critical but the femur load is not critical. For a side-facing seat, additional injury parameters may be identified and evaluation of those parameters would be necessary to provide an acceptable level of safety.

When evaluating side-facing seats the following should be taken into consideration:

1. The isolation of one occupant from another. Occupants should not rely on impact with other occupants to provide energy absorption; body-to-body impacts are unacceptable.

2. The restraint system and the retention of occupants in the seat. Addressing this concern may necessitate providing a means of restraint for the Start Printed Page 48844lower limbs as well as the torso. Failure to limit the forward (in the airplane's coordinate system) travel of the lower limbs may cause the occupant to come out of the restraint system or produce severe injuries due to the resulting position of the restraint system and/or twisting (torsional load) of the lower lumber spinal column.

3. The load limit in the torso in the lateral direction. Human tolerance for side-facing seats differs from that for forward- or aft-facing seats.

The automotive industry has developed test procedures and occupant injury criteria appropriate for side impact conditions. The criteria includes limiting lateral pelvic accelerations and using the “Thoracic Trauma Index,” which is defined in 49 CFR 571.214. Use of the Side Impact Dummy (SID) identified in 49 CFR part 572, subpart F, rather than the Hybrid II dummy identified in 49 CFR part 572, subpart B, is required to evaluate these parameters. The Hybrid II dummy is used in the current § 25.562 test. Testing with a SID is the best means available to assess the injury potential of a sideward impact condition. Such an evaluation is considered necessary to provide an acceptable level of safety for side-facing seats.

The side-facing seat special conditions have been determined to result in a level of safety equivalent to that provided by the injury pass/fail criteria in § 25.562 for forward- or aft-facing seats.


As discussed above, these special conditions are applicable to Gulfstream Model G150 airplanes. Should GALP 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.


This action affects only certain novel or unusual design features on Gulfstream Model G150 airplanes. It is not a rule of general applicability and affects only the applicant who applied to the FAA for approval of these features on the airplane.

The substance of these special conditions has been subjected to the notice and comment period in several prior instances and has been derived without substantive change from those previously issued. It is unlikely that prior public comment would result in a significant change from the substance contained herein. For this reason, and because a delay would significantly affect the certification of the airplane, which is imminent, the FAA has determined that prior public notice and comment are unnecessary and impracticable, and good cause exists for adopting these special conditions upon issuance. The FAA is requesting comments to allow interested persons to submit views that may not have been submitted in response to the prior opportunities for comment described above.

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List of Subjects in 14 CFR Part 25

  • Aircraft
  • Aviation safety
  • Reporting and recordkeeping requirements
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The authority citation for these special conditions is as follows:

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

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The Special Conditions

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Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the type certification basis for Gulfstream Model G150 airplanes.

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In addition to the airworthiness standards of §§ 25.562 and 25.785, the minimum acceptable standards for dynamic certification of single-occupant side-facing seats on Gulfstream Model G150 airplanes are as follows:

Additional Injury Criteria

(a) Existing Criteria: All injury protection criteria of §§ 25.562(c)(1) through (c)(6) apply to the occupant of a side-facing seat. Head Injury Criterion (HIC) assessments are required only for head contact with the seat and/or adjacent structures.

(b) Body-to-Wall/Furnishing Contact: The seat must be installed immediately aft of a structure, such as an interior wall or furnishing, that will support the pelvis, upper arm, chest, and head of an occupant seated next to the structure. A conservative representation of the structure and its stiffness must be included in the tests. It is recommended, but not required, that the contact surface of this structure be covered with at least two inches of energy-absorbing protective padding (foam or equivalent), such as Ensolite.

(c) Thoracic Trauma: The Thoracic Trauma Index (TTI) injury criterion must be substantiated by dynamic test or by rational analysis, based on a previous test or tests of a similar seat installation. Testing must be conducted with a Side Impact Dummy (SID), as defined in 49 CFR part 572, subpart F, or its equivalent. The TTI must be less than 85, as defined in 49 CFR part 572, subpart F. The TTI data must be processed as defined in Federal Motor Vehicle Safety Standard (FMVSS) part 571.214, section S6.13.5.

(d) Pelvis: Pelvic lateral acceleration must be shown by dynamic test or by rational analysis based on previous test(s) of a similar seat installation to not exceed 130g. Pelvic acceleration data must be processed as defined in FMVSS part 571.214, section S6.13.5.

(e) Shoulder Strap Loads: Where upper torso straps (shoulder straps) are used for occupants, tension loads in individual straps must not exceed 1,750 pounds. If dual straps are used for restraining the upper torso, the total strap tension loads must not exceed 2,000 pounds.

Additional Test Requirements

The above performance measures must not be exceeded during the following dynamic tests:

(a) Conduct a longitudinal test per § 25.562(b)(2) with a SID, undeformed floor, no yaw, and with all lateral structural supports (armrests/walls).

Pass/fail injury assessments: The TTI and pelvic acceleration.

(b) Conduct a longitudinal test per § 25.562(b)(2) with the Hybrid II Anthropomorphic Test Dummy (ATD), deformed floor, 10 degrees yaw, and with all lateral structural supports (armrests/walls).

Pass/fail injury assessments: The HIC, upper torso restraint load, restraint system retention and pelvic acceleration.

(c) Conduct a vertical test per § 25.562(b)(1) with a Hybrid II ATD with existing pass/fail criteria.

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Issued in Renton, Washington, on August 9, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 05-16517 Filed 8-19-05; 8:45 am]