Special Conditions: Boeing Model 717-200 Airplane; Operation Without Normal Electrical Power

[Federal Register Volume 64, Number 96 (Wednesday, May 19, 1999)]
[Rules and Regulations]
[Pages 27175-27177]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-12608]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM152; Special Conditions No. 25-144-SC]


Special Conditions: Boeing Model 717-200 Airplane; Operation 
Without Normal Electrical Power

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Model 717-
200 airplane. This airplane will have novel or unusual design features 
associated with its electronic flight and engine control systems. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. 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.

EFFECTIVE DATE: June 18, 1999.

FOR FURTHER INFORMATION CONTACT: Gerry Lakin, FAA, Standardization 
Branch, ANM-113, Transport Standards Staff, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, Washington, 98055-4056; telephone (425) 227-1187, facsimile 
(425) 227-1149.

SUPPLEMENTARY INFORMATION:

Background

    On August 8, 1994, the Los Angeles Aircraft Certification Office 
received an application from the McDonnell Douglas Corporation, now a 
wholly owned subsidiary of The Boeing Company, informing the FAA of 
their intention to seek an amendment to FAA Type Certificate No. A6WE 
to add the new Model MD-95-30, which was later renamed the Boeing Model 
717-200.
    The Boeing Model 717-200 is a derivative of the DC-9/MD-80/MD-90 
series of airplanes, Type Certificate No. A6WE, and is scheduled to be 
certificated in September 1999. The Boeing Model 717-200 is a low-wing, 
pressurized airplane with twin, body-mounted, jet engines that is 
configured for approximately 100 passengers. The airplane has a maximum 
takeoff weight of 121,000 pounds, a maximum landing weight of 104,000 
pounds, a maximum operating altitude of 37,000 feet, and a range of 
1500 nautical miles at a cruise speed of Mach 0.76. The overall length 
of the Boeing Model 717-200 is 124 feet, the height is 29 feet, 1 inch, 
and the wing span is 93 feet, 4 inches. Features have been added to the 
Boeing Model 717-200 to provide cost-efficient performance and 
decreased crew workload. These features include an advanced flight 
compartment, BMW/Rolls-Royce BR715 engines, an advanced auxiliary power 
unit (APU), advanced environmental systems, and an updated interior.
    The advanced flight compartment includes an electronic instrument 
system, with six liquid crystal displays, to show navigation, engine, 
and system data. For decreased crew workload, the Boeing Model 717-200 
has a flight management system and an autoflight system, with Category 
IIIa autoland capability. A central fault display system allows 
maintenance personnel access to fault data to perform return-to-service 
tests.
    The Boeing Model 717-200 is equipped with two electronically 
controlled BMW/Rolls-Royce BR715 high-bypasss ratio engines capable of 
supplying up to 21,000 pounds of thrust. For reverse thrust, the engine 
has fixed pivot door type thrust reversers.
    The advanced APU is a simple design with a single-stage compressor 
and turbine. The APU uses modular components for increased reliability 
and decreased maintenance and is controlled by an electronic control 
unit.
    The Boeing Model 717-200 has a simplified pneumatic system to 
supply bleed-air for the airplane systems. The dual cabin pressure 
control system has automatic control, with a manual backup.
    The passenger compartment interior has overhead stowage 
compartments, forward and aft lavatories, and two forward service 
galleys. The interior also has a full-grip lighted handrail attached to 
the overhead stowage compartments, for safety and convenience. Class C 
cargo compartments are located in the lower forward and aft ends of the 
airplane.

Type Certification Basis

    Under the provisions of Sec. 21.101, The Boeing Company must show 
that the Model 717-200 meets the applicable provisions of the 
regulations incorporated by reference in Type Certificate No. A6WE or 
the applicable regulations in effect on the date of application for the 
change to the Model 717-200. 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. A6WE are as follows:
    The type certification basis for the Boeing Model 717-200 airplane 
is 14 CFR part 25, effective February 1, 1965, as amended by Amendments 
25-1 through 25-82, except for certain reversions to earlier amendments 
for parts of the airplane not affected by these special conditions.
    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 Boeing Model 717-200 because of a 
novel or unusual design feature,

[[Page 27176]]

special conditions are prescribed under the provisions of Sec. 21.16.
    In addition, to the applicable airworthiness regulations and 
special conditions, the Model 717-200 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 appropriate, are issued in accordance with 
Sec. 11.49 after public notice, as required by Secs. 11.28 and 
11.29(b), and become part of the type certification basis in accordance 
with Sec. 21.101(b)(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, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design feature, the special conditions would also apply to the 
other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The Boeing Model 717-200 will incorporate the following novel or 
unusual design features:
    The Boeing Model 717-200 airplane will utilize electronic flight 
and engine control systems that establish the criticality of the 
electrical power generation and distribution systems. Since the loss of 
all electrical power may be catastrophic to the airplane, a special 
condition is proposed to retain the level of safety envisioned by 
Sec. 25.1351(d).
    The Boeing Model 717-200 airplane will require a continuous source 
of electrical power in order for the electronic flight instrument 
system to remain operable. Section Sec. 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 analog/mechanical flight instrumentation, which allows 
the crew to sort out the electrical failure, start engine(s) if 
necessary, and re-establish some of the electrical power generation 
capability. However, with today's aircraft, complex electronic/avionics 
systems are now performing critical functions that may require 
uninterrupted electrical power for continued safe flight (in instrument 
meteorological conditions (IMC)) and landing.
    In addition, Sec. 121.161 states that an operator may fly a twin-
engine airplane over a route that allows up to one-hour flying time 
from a suitable airport. If Boeing seeks operational approval for 
extended over water operations, with a possible diversion time of one 
hour, the emergency power system must be capable of providing at least 
one hour of operation to critical and essential systems. If, however, 
Boeing intends to exclude extended over water operations, then only 30 
minutes of emergency power will be required.
    In order to maintain the same level of safety associated with 
traditional designs, the Boeing Model 717-200 design must provide at 
least 30 minutes of emergency power without the normal source of engine 
or APU generated electrical power. It should be noted that service 
experience has shown that the loss of all electrical power generated by 
the airplane's engine generators or APU is not extremely improbable. 
Thus, it must be demonstrated that the airplane can continue through 
safe flight and landing 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:

1. Continue to operate the airplane for immediate safety without the 
need for crew action following the loss of the normal engine (which 
includes APU power) generator electrical power system,
2. Supply electrical power required for continued safe flight and 
landing, and
3. Supply electrical power required to restart the engines.

For compliance purposes a test demonstration of the loss of normal 
engine generator power is to be established such that:
1. The failure condition is assumed to occur during night IMC at the 
most critical phase of the flight relative to the electrical power 
system design and distribution of equipment loads on the system.
2. The airplane engine restart capability must be provided and 
operations continued in IMC after the unrestorable loss of normal 
engine generator power.
3. The airplane is demonstrated to be capable of continuous 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.

Discussion of Comments

    Notice of Proposed Special Conditions No. 25-99-01-SC for the 
Boeing Model 717-200 series airplanes was published in the Federal 
Register on March 25, 1999 (64 FR 14408). One commenter responded and 
had no objection to the special conditions. The special conditions are 
adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 717-200 airplanes. Should the McDonnell Douglas 
Corporation, now a wholly owned subsidiary of The Boeing Company 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(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on Boeing Model 717-200 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 Special Conditions

    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 Boeing Model 717-200 airplanes.

1. Operation Without Normal Electrical Power. In lieu of compliance 
with Sec. 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 (electrical power sources excluding the battery and any other 
standby electrical sources). The airplane operation must 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.''


[[Page 27177]]


    Issued in Renton, Washington on May 11, 1999.
Donald E. Gonder,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 99-12608 Filed 5-18-99; 8:45 am]
BILLING CODE 4910-13-P