DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2019-0392; Product Identifier 2019-CE-020-AD; Amendment
39-19639; AD 2019-08-51]
Airworthiness Directives; Cirrus Design Corporation
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule; request for comments.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Cirrus Design Corporation (Cirrus) Model SF50 airplanes. This AD was
sent previously as an emergency AD to all known U.S. owners and
operators of these airplanes. This AD requires replacing the angle of
sensors with improved AOA sensors. This AD was prompted by three
incidents on Cirrus Model SF50 airplanes of the stall warning and
protection system (SWPS) or Electronic Stability & Protection (ESP)
System engaging when not appropriate. The FAA is issuing this AD to
address the unsafe condition on these products.
DATES: This AD is effective June 17, 2019 to all persons except
persons to whom it was made immediately effective by Emergency AD 2019-
08-51, issued on April 18, 2019, which contained the requirements of
The Director of the Federal Register approved the incorporation by
reference of a certain publication identified in this AD as of June 17,
The FAA must receive comments on this AD by August 1, 2019.
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
for submitting comments.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this final rule, contact
Cirrus Worldwide Headquarters, 4515 Taylor Circle, Duluth, Minnesota
55811; telephone: (800) 921-2737 or after hours (800) 921-2737; fax:
(218) 788-3500; email: firstname.lastname@example.org; internet:
https://cirrusaircraft.com/service-support/. You may view this
referenced service information at the FAA, Policy and Innovation, 901
Locust, Kansas City, Missouri 64106. For information on the
availability of this material at the FAA, call (816) 329-4148. It is
also available on the internet at http://www.regulations.gov by
searching for locating Docket No. FAA-2019-0392.
Examining the AD Docket
You may examine the AD docket on the internet at http://www.regulations.gov
searching for and locating Docket No. FAA-2019-
0392; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, the regulatory evaluation, any comments received, and
other information. The street address for Docket Operations (phone:
800-647-5527) is listed above. Comments will be available in the AD
docket shortly after receipt.
FOR FURTHER INFORMATION CONTACT: Wess Rouse, Small Airplane Program
Manager, 2300 East Devon Avenue, Room 107, Des Plaines, Illinois 60018;
telephone: (847) 294-8113; fax: (847) 294-7834; email:
On April 18, 2019, we issued Emergency AD 2019-08-51, which
requires replacing the AOA sensors with improved AOA sensors. Emergency
AD 2019-08-51 was sent previously to all known U.S. owners and
operators of Cirrus Model SF50 airplanes. This action was prompted by
reports of three incidents on Cirrus Model SF50 airplanes of the SWPS
or ESP System engaging when not appropriate. The SWPS or ESP systems
may engage even when sufficient airspeed and proper angle of AOA exists
for normal flight. The SWPS includes the stall warning alarm, stick
shaker, and stick pusher. The ESP includes under speed protection
(USP). The SWPS or the ESP systems engaging inappropriately could
potentially result in a stall warning crew alert (CAS) message
activation, accompanied by an audio alarm and stick shaker activation,
followed possibly by either low speed ESP/USP engaging, and the stick
pusher engaging. The pilot will also observe the dynamic and color-
coded (Red) airspeed awareness ranges displaying the stall band,
regardless of actual indicated airspeed.
The information below presents detailed information on the three
1. While the airplane was under manual pilot control, the airplane
activated several downward pitch commands coincident with stall
warning, stick shaker, and several associated alerts. The pilot
reported ``AOA FAIL'' and ``STICK PUSHER FAIL CAS'' messages preceding
the pitch command. The pilot was able to stop the automatic pitch
commands by pressing and holding the autopilot disconnect button in
accordance with the emergency procedure in the airplane flight manual
and safely landed at his destination.
2. The operator reported stall warning and stick pusher failure in
3. The airspeed indicator went red and the stall warning and stick
shaker were heard and felt while on descent. The autopilot was
disengaged with the same results. The system settled with stick pusher
fail, stall warning fail, and LSA fail under the airspeed. The pilot
hand flew the approach and had no VREF indicator but AOA
appeared to be operating normally.
Cirrus and Aerosonic (manufacturer of the technical standard order
AOA sensor) have identified the probable root cause as an AOA sensor
malfunction due to a quality escape in the assembly of the AOA sensor
at Aerosonic. Two set screws that secure the potentiometer shaft to the
AOA vane shaft may have improper torqueing and no application of thread
locker (Loctite) to secure the two set screws. The AOA sensor with this
quality escape is labeled with part number 4677-03.
Potential erroneous AOA derived indications may occur before,
during, and after unintended automatic control system engagement. These
indications include an abnormal appearing low speed red band or VREF
green donut presented on the airspeed tape. Failed indications or
intermittent indication may result in one or more of the following:
Unintended automatic flight control activations;
The flight crew having difficulty controlling the
Excessive nose-down attitude; and/or
Possible impact with terrain.
We are issuing this AD to address the unsafe condition on these
Related Service Information Under 1 CFR Part 51
The FAA reviewed Cirrus Design Corporation SF50 Service Bulletin
Number: SB5X-34-03, dated April 16, 2019 (SB5X-34-03). The service
information provides instructions for replacing the AOA sensor with an
improved flight sensor. The FAA also reviewed Cirrus SF50 Alert Service
Advisory SA19-08, dated April 8, 2019. This service information
provides instructions for the pilot to follow in the event the AOA
sensor fails in flight.his service information is reasonably available
because the interested parties have access to it through their normal
course of business or by the means identified in the ADDRESSES section.
The FAA is issuing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of these same type
FAA's Justification and Determination of the Effective Date
An unsafe condition exists that required the immediate adoption of
Emergency AD 2019-08-51, issued on April 18, 2019, to all known U.S.
owners and operators of these airplanes. The FAA found that the risk to
the flying public justified waiving notice and comment prior to
adoption of this rule because the noted condition presents an immediate
danger to pilots and passengers of Cirrus Model SF50 airplanes. An
uncommanded pitch down may be difficult to recover from in some flight
regimes with potential fatal consequences. The before further flight
compliance time to replace the AOA sensors due to the potential fatal
consequences does not allow for prior notice and opportunity to comment
for the public.
These conditions still exist and the AD is hereby published in the
Federal Register as an amendment to section 39.13 of the Federal
Aviation Regulations (14 CFR 39.13) to make it effective to all
persons. Therefore, the FAA finds good cause that notice and
opportunity for prior public comment are impracticable. In addition,
for the reason(s) stated above, the FAA finds that good cause exists
for making this amendment effective in less than 30 days.
Differences Between This AD and the Service Information
SB5X-34-03 specifies 5 hours time-in-service (TIS) before replacing
the AOA sensors. The FAA determined that allowing 5 hours TIS to
replace the AOA sensors does not mitigate the unsafe condition; thus,
this AD requires such replacement before further flight.
This AD is a final rule that involves requirements affecting flight
safety and was not preceded by notice and an opportunity for public
comment. However, the FAA invites you to send any written data, views,
or arguments about this final rule. Send your comments to an address
listed under the ADDRESSES section. Include the docket number FAA-2019-
0392 and Product Identifier 2019-CE-020-AD at the beginning of your
comments. The FAA specifically invites comments on the overall
regulatory, economic, environmental, and energy aspects of this final
rule. The FAA will consider all comments received by the closing date
and may amend this final rule because of those comments.
The FAA will post all comments we receive, without change, to
http://www.regulations.gov, including any personal information you
provide. The FAA will also post a report summarizing each substantive
verbal contact we receive about this final rule.
Costs of Compliance
The FAA estimates that this AD affects 99 airplanes of U.S.
The FAA estimates the following costs to comply with this AD:
||Cost per product
||Cost on U.S. operators
the AOA sensor
|1.25 work-hours x $85 per hour
According to the manufacturer, all
of the costs of this AD may be
covered under warranty, thereby reducing the cost impact on affected
individuals. The FAA does not control warranty coverage for affected
individuals. As a result, the FAA has included all costs in our cost
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to small airplanes, gliders,
balloons, airships, domestic business jet transport airplanes, and
associated appliances to the Director of the Policy and Innovation
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
(2) Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
Adoption of the Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness