Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-08-12 R1
March 16, 2011
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) advises you of
an airworthiness concern on Cirrus Design Corporation (CDC) Models SR20
and SR22 airplanes where possible failure of a transient voltage
suppressor (TVS) may result in an increase in workload for the pilot.
This airworthiness action has been taken after consideration of the
responses from CDC as well as airplane owners/ operators through
relevant associations and type clubs, using the procedures found in the
Small Airplane Directorate Airworthiness Directives Manual Supplement
(Airworthiness Concern Process Guide).
At this time, this airworthiness concern is not considered an unsafe
condition that would warrant an airworthiness directive (AD) action
under Title 14 of the Code of Federal Regulations (14 CFR part 39).
This SAIB is being revised to advise you of service information
recently issued by CDC regarding the specific TVS that is the subject
of this SAIB.
Background
CDC notified the Federal Aviation Administration of the failure of a
TVS on a CDC Model SR22 airplane, which resulted in loss of NAV/COM1
functionality and some smoke and fumes within the cockpit. Since that
time, 14 other TVSs have failed on CDC airplanes in the field.
Other airplanes equipped with TVSs from the same manufacturer have
recently experienced failures. Our findings thus far, show that the
electronic component itself is the primary suspect for a cause of the
failures. To date, no specific reason has been positively identified
for the failures although several companies are working on the problem.
As previously mentioned, no other functionality other than the NAV/COMM
1 has been lost on a CDC airplane. All CDC airplanes have redundancy
with a NAV/COMM 2 available. Also, in all known occurrences of TVS
failures, the smoke and fumes have been noted to be of short duration
and not sufficient to impede the pilots visibility, or toxic such that
the pilot’s ability to operate the airplane is impaired.
Since the original release of this SAIB, there is one known additional
occurrence of a failed TVS in the NAV/COMM 1 circuit, leading to
short-term smoke in the cockpit. CDC has issued Service Bulletin number
SB 2X-24-09 to address the problem. The service bulletin adds an
in-line fuse, which will open the circuit should the TVS begin to fail.
This solution will limit the time smoke may be emitted by a failing TVS
as power is removed from the TVS rather than power remaining on the
device until it self destructs.
Recommendations
We recommend the following:
all CDC airplane
owner/operators thoroughly read Cirrus service advisory SA 07-17, dated
September 11, 2007. The service advisory provides good information on
what to expect should a TVS failure occur and what actions should be
taken by the pilot;
An owner of a Cirrus SR20 or
SR22 reference Service Bulletin SB 2X-24-09 to see if the bulletin
applies to their airplane and if it does, incorporate the actions of
the bulletin. Completion of the service bulletin will reduce or
eliminate smoke in the cockpit in the event of a TVS failure.
You may obtain the service information referenced above at: http:www.cirruslink.com/mycirrus/servicepubs.aspx
For Further Information Contact
Wesley Rouse, Aerospace Engineer, FAA Chicago Aircraft Certification,
2300 E. Devon, Des Plaines, IL 60018; phone: (847) 294-8113; email:
wess.rouse@faa.gov