bakerocb
Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA
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 Posted: Wed Feb 27, 2008 10:52 am Post subject: TVS Failures |
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2/27/2008
Hello Fellow Builders, The certificated airplane community has been hit with
a series of TVS failures. Several different manufacturer's airplanes have
been affected.
Copied below is just one of the SAIB's that the FAA has issued on this
subject.
If your project includes TVS' you may want to further investigate -- the
same TVS manufacturer seems to be involved in all failures.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
-----------------------------------------------------
FAA
Aircraft Certification Service
SPECIAL AIRWORTHINESS
INFORMATION BULLETIN
SUBJ: Electrical Power
SAIB: CE-08-12
Date: 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(at)faa.gov
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