Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-08-12
February 27, 2008
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).
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 TVS’s 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.
Recommendations
We recommend that 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.
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