[Federal Register Volume 77, Number 28 (Friday, February 10, 2012)]
[Rules and Regulations]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-3077]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2012-0154; Special Conditions No. 25-457-SC]
Special Conditions: Learjet Inc., Learjet Model LJ-200-1A10;
Interaction of Systems and Structures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
SUMMARY: These special conditions are issued for the Learjet Model LJ-
200-1A10 airplane. This airplane will have novel or unusual design
features associated with systems that, directly or as a result of
failure or malfunction, affect structural performance. 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.
DATES: The effective date of these special conditions is February 3,
2012. We must receive your comments by March 26, 2012.
ADDRESSES: Send comments identified by docket number FAA-2012-0154
using any of the following methods:
Federal eRegulations Portal: Go to http://www.regulations.gov/and follow the online instructions for sending your
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC between 8 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at (202) 493-2251.
Privacy: The FAA will post all comments it receives, without
change, to http://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov/.
Docket: Background documents or comments received may be read at
http://www.regulations.gov/at any time. Follow the online instructions
for accessing the docket or go to the Docket Operations in Room W12-140
of the West Building Ground Floor at 1200 New Jersey Avenue SE.,
Washington, DC between 9 a.m. and 5 p.m., Monday through Friday, except
FOR FURTHER INFORMATION CONTACT: Todd Martin, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone (425) 227-1178; facsimile (425) 227-1320.
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for public comments on, these special conditions are
unnecessary. 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.
We invite interested people to take part in this rulemaking by
sending 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 will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
On February 9, 2009, Learjet Inc. applied for a type certificate
for their new Model LJ-200-1A10 (hereafter referred to as ``Model LJ-
200'') airplane. The Model LJ-200 is a business class aircraft powered
by 2 high bypass turbine engines with an estimated maximum takeoff
weight of 36,000 pounds and an interior configuration for up to 10
The airplane is equipped with systems that, directly or as a result
of failure or malfunction, affect its structural performance. Current
regulations do not take into account loads for the aircraft due to the
effects of system failures on structural performance. These special
conditions define criteria to be used in the assessment of the effects
of these systems on structures. The general approach of accounting for
the effect of system failures on structural performance would be
extended to include any system whose partial or complete failure, alone
or in combination with other system failures, would affect structural
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, Learjet Inc. must show that the Model LJ-200 meets the
applicable provisions of part 25, as amended by Amendments 25-1 through
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 LJ-200 because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
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 or similar
novel or unusual design feature, these special conditions would also
apply to the other model.
In addition to the applicable airworthiness regulations and special
conditions, the Model LJ-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; and the FAA must issue a finding of
regulatory adequacy pursuant to Sec. 611 of Public Law 92-574, the
``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The Model LJ-200 will incorporate the following novel or unusual
features: systems that affect the airplane's structural performance,
either directly or as a result of failure or malfunction. That is, the
airplane's systems affect how it responds in maneuver and gust
conditions, and thereby affect its structural capability. These systems
may also affect the aeroelastic stability of the airplane. Such systems
include flight control systems, autopilots, stability augmentation
systems, load alleviation systems, and fuel management systems. Such
systems represent novel and unusual features when compared to the
technology envisioned in the current airworthiness standards.
Special conditions are needed to require consideration of the
effects of systems on the structural capability and aeroelastic
stability of the airplane, both in the normal and in the failed state,
because these effects are not covered by current regulations.
These special conditions require that the airplane meet the
structural requirements of subparts C and D of 14 CFR part 25 when the
airplane systems are fully operative. The special conditions also
require that the airplane meet these requirements considering failure
conditions. In some cases, reduced margins are allowed for failure
conditions based on system reliability.
These special conditions establish a level of safety that neither
raises nor lowers the standard set forth in the applicable regulations.
As discussed above, these special conditions are applicable to the
Learjet Model LJ-200-1A10. Should Learjet Inc. apply at a later date
for a change to the type certificate to include another model
incorporating the same novel or unusual design features, the special
conditions would apply to that model as well.
This action affects only certain novel or unusual design features
on one model of airplanes. It is not a rule of general applicability.
The substance of these special conditions has been subjected to the
notice and comment period in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. Therefore, the FAA has determined
that prior public notice and comment are unnecessary and impracticable,
and good cause exists for adopting these special conditions upon
issuance. The FAA is requesting comments to allow interested persons to
submit views that may not have been submitted in response to the prior
opportunities for comment described above.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
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 Learjet Model LJ-200-1A10 airplanes.
For airplanes equipped with systems that affect structural
performance, either directly or as a result of a failure or
malfunction, the influence of these systems and their failure
conditions on structural performance must be taken into account when
showing compliance with the requirements of 14 CFR part 25, subparts C
and D. The following criteria must be used for showing compliance with
these special conditions for airplanes equipped with flight control
systems, autopilots, stability augmentation systems, load alleviation
systems, fuel management systems, and other systems that either
directly or as a result of failure or malfunction affect structural
(a) The criteria defined herein only address the direct structural
consequences of the system responses and performances. They cannot be
considered in isolation but should be included in the overall safety
evaluation of the airplane. These criteria may in some instances
duplicate standards already established for this evaluation. These
criteria are only applicable to structures whose failure could prevent
continued safe flight and landing. Specific criteria that define
acceptable limits on handling characteristics or stability requirements
when operating in the system degraded or inoperative mode are not
provided in these special conditions.
(b) Depending upon the specific characteristics of the airplane,
additional studies may be required that go beyond the criteria provided
in these special conditions in order to demonstrate the capability of
the airplane to meet other realistic conditions such as alternative
gust or maneuver descriptions for an airplane equipped with a load
(c) The following definitions are applicable to these special
Structural performance: Capability of the airplane to meet the
structural requirements of part 25.
Flight limitations: Limitations that can be applied to the airplane
flight conditions following an in-flight occurrence and that are
included in the flight manual (e.g., speed limitations, avoidance of
severe weather conditions, etc.).
Operational limitations: Limitations, including flight limitations,
that can be applied to the airplane operating conditions before
dispatch (e.g., fuel, payload and Master Minimum Equipment List
Probabilistic terms: The probabilistic terms (probable, improbable,
extremely improbable) used in these special conditions are the same as
those used in Sec. 25.1309.
Failure condition: The term failure condition is the same as that
used in Sec. 25.1309; however, these special conditions apply only to
system failure conditions that affect the structural performance of the
airplane (e.g., system failure conditions that induce loads, change the
response of the airplane to inputs such as gusts or pilot actions, or
lower flutter margins).
2. Effects of Systems on Structures
The following criteria will be used in determining the influence of
a system and its failure conditions on the airplane structure.
(a) System fully operative. With the system fully operative, the
(1) Limit loads must be derived in all normal operating
configurations of the system from all the limit conditions specified in
subpart C (or defined by special condition or equivalent level of
safety in lieu of those specified in Subpart C), taking into account
any special behavior of such a system or associated functions or any
effect on the structural performance of the airplane that may occur up
to the limit loads. In particular, any significant nonlinearity (rate
of displacement of control surface, thresholds, or any other system
nonlinearities) must be accounted for in a realistic or conservative
way when deriving limit loads from limit conditions.
(2) The airplane must meet the strength requirements of part 25
(static strength, residual strength), using the specified factors to
derive ultimate loads from the limit loads defined above. The effect of
nonlinearities must be
investigated beyond limit conditions to ensure the behavior of the
system presents no anomaly compared to the behavior below limit
conditions. However, conditions beyond limit conditions need not be
considered when it can be shown that the airplane has design features
that will not allow it to exceed those limit conditions.
(3) The airplane must meet the aeroelastic stability requirements
of Sec. 25.629.
(b) System in the failure condition. For any system failure
condition not shown to be extremely improbable, the following apply:
(1) At the time of occurrence, starting from 1-g level flight
conditions, a realistic scenario including pilot corrective actions
must be established to determine the loads occurring at the time of
failure and immediately after failure.
(i) For static strength substantiation, these loads, multiplied by
an appropriate factor of safety that is related to the probability of
occurrence of the failure, are ultimate loads to be considered for
design. The factor of safety is defined in Figure 1.
[GRAPHIC] [TIFF OMITTED] TR10FE12.000
(ii) For residual strength substantiation, the airplane must be
able to withstand two thirds of the ultimate loads defined in
subparagraph 2(b)(1)(i) of these special conditions. For pressurized
cabins, these loads must be combined with the normal operating
(iii) Freedom from aeroelastic instability must be shown up to the
speeds defined in Sec. 25.629(b)(2). For failure conditions that
result in speeds beyond VC/MC, freedom from
aeroelastic instability must be shown to increased speeds, so that the
margins intended by Sec. 25.629(b)(2) are maintained.
(iv) Failures of the system that result in forced structural
vibrations (oscillatory failures) must not produce loads that could
result in detrimental deformation of primary structure.
(2) For the continuation of the flight. For the airplane, in the
system failed state and considering any appropriate reconfiguration and
flight limitations, the following apply:
(i) The loads derived from the following conditions (or defined by
special condition or equivalent level of safety in lieu of the
following conditions) at speeds up to VC/MC, or
the speed limitation prescribed for the remainder of the flight, must
(A) The limit symmetrical maneuvering conditions specified in Sec.
25.331 and in Sec. 25.345.
(B) The limit gust and turbulence conditions specified in Sec.
25.341 and in Sec. 25.345.
(C) The limit rolling conditions specified in Sec. 25.349 and the
limit unsymmetrical conditions specified in Sec. 25.367 and Sec.
25.427(b) and (c).
(D) The limit yaw maneuvering conditions specified in Sec. 25.351.
(E) The limit ground loading conditions specified in Sec. Sec.
25.473, 25.491, 25.493(d) and 25.503.
(ii) For static strength substantiation, each part of the structure
must be able to withstand the loads in paragraph 2(b)(2)(i) of these
special conditions multiplied by a factor of safety depending on the
probability of being in this failure state. The factor of safety is
defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TR10FE12.001
Qj = (Tj)(Pj)
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per
Note: If Pj is greater than 10-3 per
flight hour, then a 1.5 factor of safety must be applied to all
limit load conditions specified in Subpart C.
(iii) For residual strength substantiation, the airplane must be
able to withstand two thirds of the ultimate loads defined in paragraph
2(b)(2)(ii) of these special conditions. For pressurized cabins, these
loads must be combined with the normal operating differential pressure.
(iv) If the loads induced by the failure condition have a
significant effect on fatigue or damage tolerance, then their effects
must be taken into account.
(v) Freedom from aeroelastic instability must be shown up to a
speed determined from Figure 3. Flutter clearance speeds V' and V'' may
be based on the speed limitation specified for the remainder of the
flight using the margins defined by Sec. 25.629(b).
[GRAPHIC] [TIFF OMITTED] TR10FE12.002
V1' = Clearance speed as defined by Sec. 25.629(b)(2).
V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Qj = (Tj)(Pj)
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per
Note: If Pj is greater than 10-\3\ per
flight hour, then the flutter clearance speed must not be less than
(vi) Freedom from aeroelastic instability must also be shown up to
V' in Figure 3 above for any probable system failure condition combined
with any damage required or selected for investigation by Sec.
(3) Consideration of certain failure conditions may be required by
other sections of part 25 regardless of calculated system reliability.
Where analysis shows the probability of these failure conditions to be
less than 10-\9\, criteria other than those specified in
this paragraph may be used for structural substantiation to show
continued safe flight and landing.
(c) Failure indications. For system failure detection and
indication, the following apply:
(1) The system must be checked for failure conditions, not
extremely improbable, that degrade the structural capability below the
level required by part 25 or significantly reduce the reliability of
the remaining system. As far as reasonably practicable, the flight crew
must be made aware of these failures before flight. Certain elements
of the control system, such as mechanical and hydraulic components, may
use special periodic inspections, and electronic components may use
daily checks, in lieu of detection and indication systems to achieve
the objective of this requirement. These certification maintenance
requirements must be limited to components that are not readily
detectable by normal detection and indication systems and where service
history shows that inspections will provide an adequate level of
(2) The existence of any failure condition, not extremely
improbable, during flight that could significantly affect the
structural capability of the airplane and for which the associated
reduction in airworthiness can be minimized by suitable flight
limitations, must be signaled to the flight crew. For example, failure
conditions that result in a factor of safety between the airplane
strength and the loads of Subpart C below 1.25, or flutter margins
below V'', must be signaled to the crew during flight.
(d) Dispatch with known failure conditions. If the airplane is to
be dispatched in a known system failure condition that affects
structural performance, or affects the reliability of the remaining
system to maintain structural performance, then the provisions of these
special conditions must be met, including the provisions of paragraph
2(a) for the dispatched condition, and paragraph 2(b) for subsequent
failures. Expected operational limitations may be taken into account in
establishing Pj as the probability of failure occurrence for
determining the safety margin in Figure 1. Flight limitations and
expected operational limitations may be taken into account in
establishing Qj as the combined probability of being in the
dispatched failure condition and the subsequent failure condition for
the safety margins in Figures 2 and 3. These limitations must be such
that the probability of being in this combined failure state and then
subsequently encountering limit load conditions is extremely
improbable. No reduction in these safety margins is allowed if the
subsequent system failure rate is greater than 10-\3\ per
For each system for which these special conditions are applied, the
following must be identified for showing compliance:
(a) The system that either directly or as a result of failure or
malfunction affects structural performance;
(b) The failure condition of the system and the probability of that
(c) The structure whose performance is affected directly or as a
result of failure or malfunction of the system; and,
(d) The loading condition(s) on the structure affected by the
Issued in Renton, Washington, on February 3, 2012.
Manager, Transport Airplane Directorate, Aircraft Certification
[FR Doc. 2012-3077 Filed 2-9-12; 8:45 am]
BILLING CODE 4910-13-P