Source: https://www.federalregister.gov/documents/2005/10/04/05-19858/special-conditions-boeing-model-720b-high-intensity-radiated-fields-hirf
Timestamp: 2017-08-21 02:55:46
Document Index: 247810173

Matched Legal Cases: ['art 25', '§\u200921', 'art 24', 'art 36', '§\u200921', 'art 25']

Federal Register :: Special Conditions: Boeing Model 720B; High Intensity Radiated Fields (HIRF)
Special Conditions: Boeing Model 720B; High Intensity Radiated Fields (HIRF)
A Rule by the Federal Aviation Administration on 10/04/2005
The effective date of these special conditions is September 12, 2005. Comments must be received on or before November 3, 2005.
70 FR 57726
57726-57728 (3 pages)
Docket No. NM327, Special Conditions No. 25-297-SC
05-19858
https://www.federalregister.gov/d/05-19858 https://www.federalregister.gov/d/05-19858
These special conditions are issued for the Boeing Model 720B airplane. The airplane will have novel and unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification Start Printed Page 57727incorporates the installation of dual Honeywell AM-250 digital altimeters. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for the protection of these systems from the effects of high-intensity radiated fields (HIRF). These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that provided by the existing airworthiness standards.
Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attn: Rules Docket (ANM-113), Docket No. NM327, 1601 Lind Avenue, SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. All comments must be marked: Docket No. NM327. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
Mr. Greg Dunn, FAA, Airplane & Flight Crew Interface Branch, ANM-111, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW., Renton, Washington, 98055-4056; telephone (425) 227-2799; facsimile (425) 227-1149.
The FAA has determined that notice and opportunity for prior public comment hereon is unnecessary, as 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; however, the FAA invites interested persons to participate in this rulemaking by submitting 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.
On July 5, 2005, Flight Test Associates, Inc., of Mojave, California, applied to the FAA, Los Angeles Aircraft Certification Office for a supplemental type certificate (STC) to modify a Boeing Model 720B airplane. The proposed modification incorporates the installation of dual Honeywell AM-250 digital altimeters as primary instruments. The information presented is flight critical. The altimeter installed in the airplane has the potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.
Under the provisions of 14 CFR 21.101, Flight Test Associates, Inc., must show that the Boeing Model 720B airplane, as changed, continues to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. 4A28, or the applicable regulations in effect on the date of application for the change. The regulations incorporated by reference in the type certificate are commonly referred to as the “original type certification basis.”
The regulations incorporated by reference in Type Certificate No. 4A28 include Civil Aeronautics Manual 4b, as amended by Amendments 4b-1 through 4b-6.
If the Administrator finds that the applicable airworthiness regulations (i.e., part 25, as amended) do not contain adequate or appropriate safety standards for the modified Boeing Model 720B airplane, 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 Boeing Model 720B airplane must comply with the fuel vent and exhaust emission requirements of 14 CFR part 24 and the noise certification requirements of 14 CFR part 36.
Special conditions are initially applicable to the model for which they are issued. Should Flight Test Associates, Inc., apply at a later date for an STC to modify any other model included on the same type certificate to incorporate the same novel or unusual design feature, these special conditions would also apply to the other model under the provisions of § 21.101.
As noted earlier, the Boeing Model 720B airplane modified by Flight Test Associates, Inc., will incorporate new dual primary altimeters that will perform critical functions. These systems may be vulnerable to HIRF external to the airplane. The current airworthiness standards of part 25 do not contain adequate or appropriate safety standards for the protection of this equipment from the adverse effects of HIRF. Accordingly, this system is considered to be a novel or unusual design feature.
To ensure that a level of safety is achieved equivalent to that intended by the regulations incorporated by reference, special conditions are needed for the Boeing Model 720B airplane modified by Flight Test Associates, Inc. These special conditions require that new primary altimeters that perform critical functions be designed and installed to preclude component damage and interruption of function due to both the direct and indirect effects of HIRF.
With the trend toward increased power levels from ground-based transmitters, plus the advent of space and satellite communications coupled with electronic command and control of the airplane, the immunity of critical digital avionics/electronics and Start Printed Page 57728electrical systems to HIRF must be established.
As discussed above, these special conditions are applicable to Boeing Model 720B airplane, modified by Flight Test Associates, Inc. Should Flight Test Associates, Inc., apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design feature, these special conditions would apply to that model as well as under the provisions of 14 CFR 21.101.
This action affects only certain design features on the Boeing Model 720B airplane modified by Flight Test Associates, Inc. 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.
Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the supplemental type certification basis for the Boeing Model 720B airplane, modified by Flight Test Associates, Inc:
[FR Doc. 05-19858 Filed 10-3-05; 8:45 am]