Source: https://www.federalregister.gov/documents/2015/08/18/2015-20297/special-conditions-gulfstream-model-gvii-g500-airplanes-automatic-speed-protection-for-design-dive
Timestamp: 2018-04-26 16:22:47
Document Index: 623617035

Matched Legal Cases: ['art 25', 'art 34', 'art 36', '§\u2009611', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925']

80 FR 49936
49936-49938 (3 pages)
Notice No. 25-15-08-SC
https://www.federalregister.gov/d/2015-20297 https://www.federalregister.gov/d/2015-20297
This action proposes special conditions for the Gulfstream Model GVII-G500 airplanes. These airplanes will have a novel or unusual design feature associated with a reduced margin between design cruising speed, VC/MC, and design diving speed, VD/MD, based on the incorporation of a high-speed protection system that limits nose-down pilot authority at speeds above VC/MC. 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.
Send comments identified by docket number FAA-2015-1482 using any of the following methods:
On March 29, 2012, Gulfstream Aerospace Corporation applied for a type certificate for their new Model GVII-G500 airplane. The Model GVII-G500 airplane will be a large-cabin business jet with seating for 19 passengers. It will incorporate a low, swept-wing design with winglets and a T-tail. The powerplant will consist of two aft-fuselage-mounted Pratt & Whitney turbofan engines. Avionics will include four primary display units and multiple touchscreen controllers. The flight-control system is a three-axis, fly-by-wire system incorporating active control/coupled side sticks.
The Model GVII-G500 will have a wingspan of approximately 87 feet and a length of just over 91 feet. Maximum takeoff weight will be approximately 76,850 pounds and maximum takeoff thrust will be approximately 15,135 pounds. Maximum range will be Start Printed Page 49937approximately 5,000 nautical miles, and maximum operating altitude will be 51,000 feet.
Under the provisions ofTitle 14, Code of Federal Regulations (14 CFR) 21.17, Gulfstream must show that the Model GVII-G500 airplane meets the applicable provisions of part 25 as amended by Amendments 25-1 through 25-137.
In addition, the certification basis includes other regulations, special conditions, and exemptions that are not relevant to these proposed special conditions.
In addition to the applicable airworthiness regulations and special conditions, the Model GVII-G500 airplane 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 under § 611 of Public Law 92-574, the “Noise Control Act of 1972.”
The Model GVII-G500 airplane will incorporate the following novel or unusual design features:
Gulfstream proposes to reduce the margin between VC/MC and VD/MD, required by 14 CFR 25.335(b), based on the incorporation of a high-speed protection system in the airplane's flight-control laws. The high-speed protection system limits nose-down pilot authority at speeds above VC/MC, and prevents the airplane from performing the maneuver required under § 25.335(b)(1).
These special conditions are proposed in lieu of § 25.335(b)(1). Section 25.335(b)(2), which also addresses the design dive speed, is applied separately (Advisory Circular (AC) 25.335-1A provides an acceptable means of compliance to § 25.335(b)(2)).
Special conditions are necessary to address the Model GVII-G500 airplane high-speed protection system.These proposed special conditions identify various symmetric and non-symmetric maneuvers that will ensure that an appropriate design dive speed, VD/MD, is established.
Special Condition 2 of these proposed special conditions references AC 25-7C, section 8, paragraph 32, “Gust Upset,” included here for reference:
Special Conditions 3 and 4 of these proposed special conditions indicate that failures of the high-speed protection system must be improbable and must be annunciated to the pilots. If these two criteria are not met, then the probability that the established dive speed will be exceeded, and the resulting risk to the airplane, are too great. On the other hand, if the high-speed protection system is known to be inoperative, then dispatch of the airplane may be acceptable as allowed by proposed Special Condition 5. Dispatch would only be acceptable if appropriate reduced operating speeds, VMO/MMO, as well as the overspeed warning for exceeding those speeds, are provided in both the airplane flight manual and on the flightdeck display, and are equivalent to that of the normal airplane with the high-speed protection system operative.
We do not believe that application of the “Interaction of Systems and Structures” Special Conditions (reference GVI Issue Paper A-2), or EASA Certification Specification 25.302, are appropriate in this case, because design dive speed is, in and of itself, part of the design criteria. Stability and control, flight loads, and flutter evaluations all depend on the design dive speed. Therefore, a single design dive speed should be established Start Printed Page 49938that will not be exceeded, taking into account the performance of the high-speed protection system as well as its failure modes, failure indications, and accompanying flight-manual instructions.
As discussed above, these special conditions are applicable to the Model GVII-G500 airplane. Should Gulfstream 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.
Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for Gulfstream Model GVII-G500 airplanes.
1. In lieu of compliance with § 25.335(b)(1), if the flight-control system includes functions that act automatically to initiate recovery before the end of the 20-second period specified in § 25.335(b)(1), VD/MD must be determined from the greater of the speeds resulting from conditions (a) and (b) of these special cConditions. The speed increase occurring in these maneuvers may be calculated if reliable or conservative aerodynamic data are used.
[FR Doc. 2015-20297 Filed 8-17-15; 8:45 am]