[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
