02-12023. Special Conditions: Fairchild Dornier GmbH, Model 728-100; Operation Without Normal Electrical Power

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed special conditions.

SUMMARY:

This action proposes special conditions for the Fairchild Dornier GmbH Model 728-100 airplane. This airplane will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The airplane design will include an electronic flight control system. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions, in part, 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. Additional special conditions may also be defined.

DATES:

Comments must be received on or before June 28, 2002.

ADDRESSES:

Comments on this proposal may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-113), Docket No. NM206, 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. NM206. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT:

Tom Groves, FAA, International Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone [phone]; facsimile [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

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 proposal, 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 proposed special conditions. The docket is available for public inspection 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 action 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 the proposed special conditions in light of the comments we receive.

If you want the FAA to acknowledge receipt of your comments on this proposal, include with your comments a pre-addressed, stamped postcard on which the docket number appears. We will stamp the date on the postcard and mail it back to you.

Background

On May 5, 1998, Fairchild Dornier GmbH applied for a type certificate for their new Model 728-100 airplane. The Model 728-100 is a 70-85 passenger twin-engine regional jet with a maximum takeoff weight of 77,600 pounds.

Type Certification Basis

Under the provisions of 14 CFR 21.17, Fairchild Dornier GmbH must show that the Model 728-100 airplane meets the applicable provisions of part 25, as amended by Amendments 25-1 through 25-96. Fairchild Dornier GmbH has also applied to extend the certification basis to include Amendments 25-97, 25-98, and 25-104.

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 Model 728-100 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 Model 728-100 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 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 under the provisions of § 21.101(a)(1).

Novel or Unusual Design Features

As noted earlier, the Fairchild Dornier GmbH Model 728-100 airplane will include an electronic flight control system. The current airworthiness standards of part 25 do not contain adequate or appropriate standards for the protection of this equipment from the adverse effects of operations without normal electrical power. Accordingly, this system is considered to be a novel or unusual design feature. Since the loss of all electrical power may be catastrophic to the airplane, special conditions are proposed to retain the level of safety envisioned by § 25.1351(d).

Discussion

The Fairchild Dornier GmbH Model 728-100 airplane will require a continuous source of electrical power for the electronic flight control system. Section 25.1351(d), “Operation without normal electrical power,” requires safe operation in visual flight rule (VFR) conditions for a period of not less than five minutes with inoperative normal power. This rule was structured around a traditional design utilizing mechanical connections between the flight control surfaces and the pilot controls. The Fairchild Dornier GmbH Model 728 will utilize an electronic flight control system. With an electronic flight control system, there is no mechanical linkage between the pilot controls and the flight control surfaces. Pilot control inputs are converted to electrical signals which are processed and then transmitted via wires to the control surface actuators. At the control surface actuators the electrical signals are converted to an actuator command, which moves the control surface. Uninterrupted electrical power is necessary to ensure the electronic flight control system function.

Service experience has shown that the loss of all electrical power generated by the airplane's engine generators or auxiliary power unit (APU) is not extremely improbable. Thus, it must be demonstrated that the airplane can continue safe flight and landing after total loss of the normal electrical power with only the use of its emergency electrical power systems. These emergency electrical power systems must be able to power loads that are essential for continued safe flight and landing. The emergency electrical power system must be designed to supply:

1. Electrical power required for immediate safety, without the need for crew action, following the loss of the normal engine generator electrical power system (which includes APU power).

2. Electrical power required for continued safe flight and landing.

3. Electrical power required to restart the engines.

For compliance purposes, a test of the loss of normal engine generator power must be conducted to demonstrate that when the failure condition occurs during night instrument meteorological conditions (IMC), at the most critical phase of the flight relative to the electrical power system design and distribution of equipment loads on the system, the following conditions are met:

1 Engine restart capability is provided.

2. Capability for continued operation in IMC is provided.

3. The airplane is demonstrated to be capable of continued safe flight and landing. The length of time must be computed based on the maximum diversion time capability for which the airplane is being certified. Consideration for speed reductions resulting from the associated failure must be made.

4. The availability of APU operation should not be considered in establishing emergency power system adequacy.

Applicability

As discussed above, these special conditions are applicable to the Fairchild Dornier GmbH Model 728-100. Should Fairchild Dornier GmbH 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 under the provisions of section 21.101(a)(1). Fairchild Dornier has submitted applications for certification of both increased and reduced passenger capacity derivatives of the Model 728-100 airplane. These derivative models are designated the Model 928-100 airplane and the Model 528-100 airplane, respectively. As currently proposed, these derivative models share the same design feature of an electronic flight control system as the Model 728-100 airplane, and it is anticipated that they will be included in the applicability of these proposed special conditions.

Conclusion

This action affects only certain novel or unusual design features on Fairchild Dornier GmbH Model 728-100 airplanes. It is not a rule of general applicability, and it affects only the applicant who applied to the FAA for approval of these features on the airplane.

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:

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 Fairchild Dornier GmbH Model 728-100 airplanes.

Operation Without Normal Electrical Power. In lieu of compliance with § 25.1351(d), it must be demonstrated by test, or combination of test and analysis, that the airplane can continue safe flight and landing with inoperative normal engine and APU generator electrical power (in other words, without electrical power from any source except for the battery and any other standby electrical sources). The airplane operation should be considered at the critical phase of flight and include the ability to restart the engines and maintain flight for the maximum diversion time capability being certified.

Issued in Renton, Washington, on April 23, 2002.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.