ACS-Cessna Switch

[GAHorn]

FAA has released a ACS regarding certain Cessna Switches for 100-200-300 aircraft, Reference Service bulletins SEB09-6A, dated May 11, 2009 and MEB09-3 dated May 11, 2009.

The ACS claims that landing, taxi, and certain beacon switches have been known to fail after about 4 years and so they are considering AD action, and asking for feedback. Below is the actual ACS in pdf format for you to download if you wish to read it. Also, below is the text of my response to FAA.

To: daniel.hilton@faa.gov
1 attachment
Cessna-Sw...pdf (27.8 KB)


Dear Mr. Hilton,
This ACS is so broadly written and so sparse in information as to WHICH MODELS aircraft, WHICH SERIALS, and WHICH TYPE, MFR, BRAND, ETC. of switches, that it is not worthy of action. Unless it can be shown that a particular switch is susceptible to failure following a specific NUMBER OF CYCLES .... then the "sky is falling" approach to "switches" that are a certain age is without merit.
There have been NO "short" failures of the switches used in the Cessna 170 series that I, as parts and maintenance Advisor to the Int'l Cessna 170 Association, am aware.
This ACS has no more validity than to claim that "TIRES" AND "TUBES" of a certain age in 100/200/300/400/500 series Cessnas have been known to go flat causing a potential for loss of directional control.
Please take a reasonable approach to this ACS and require specific aircraft serials and specific switch types/models/mfr's to be analyzed, etc. before taking a "blanket" approach to such matters.
Thank you.
George Horn
Parts/MX TIC170A

Cessna-Switch-ACS.pdf

[SteveF]

Thanks George,

EXCELLENT RESPONSE !!!!!!!!!

[N2255D]

I didn't know that Cessna made their own switches to start with. I thought they bought them from the cheapest vendor they could find. Unless Cessna really does make their own switches, the FAA needs to start looking at other manufactures who use the same switches as Cessna. Then they will find out if there is a real or imagined problem.

[GAHorn]

I suspect that the actual switches that are problematical are the so-called "rocker" switches which came into vogue in the sixties. Those switches utilize a compression-spring which, once internal wear occurs, tend to dislodge and move the contacts into disarray, causing failures and shorts. In recent decades those switches have stamped upon their bodies "MEXICO" and, in fact, I've seen identical switches in non-aviation use with all the same markings and mateials. (I once had a shop vacuum cleaner with the exact same switch as my '64 C-206 Navigational lights.)

The common toggle switches used with the so-called "piano-board" of the early C-170/C170A aircraft, and the Push/Pull switches of the later B-models have never been a problem as far as shorts are concerned. (The toggles simply fail to make contact or corrode, and the Push/Pull internal contacts fail to "make" due to corrosion/loss-of-lubrication or worn spring-sliders. The toggles should simply be replaced, and the Push/Pull can be either replaced or repaired/lubricated.)
The toggles and Push/Pulls are common marine/automotive switches.

[N2255D]

FAA Aircraft Certification Service SPECIAL AIRWORTHINESS INFORMATION BULLETIN SAIB: CE-09-42 SUBJ: Lights - Landing Light, Beacon Light and Taxi Light Switch Applications Date: July 24, 2009 This is information only. Recommendations aren't mandatory. Introduction This Special Airworthiness Information Bulletin (SAIB) is being issued to advise you of an airworthiness concern on mandatory replacement intervals of Cessna Landing Light, Beacon Light, and Taxi Light switches on Cessna 100, 200, and 300 series airplanes specified per Cessna service bulletins MEB09-3 and SEB09-6 dated May 11, 2009.
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 Cessna 100, 200, and 300 series airplanes utilize switches in the Landing Light, Beacon Light, and Taxi Light circuits that have been reported failing in the field causing overheating and smoke in the cockpit. There have been reports of burned insulation on the wiring terminals to the switch. On at least one occasion, there was a small fire in the cockpit. The failure in these applications can be attributed to contact erosion leading to irregular arcing and eventual failure of the switch. The contact erosion has been shown to occur after approximately 4,000 cycles of operation. Cessna service bulletins SEB09-6 and MEB09-3, initial release, dated May 11, 2009, specify the following: o An inspection to determine time-in-service for the switches. o Replacement of switches that have been in service for four or more years with the month and year of the installation written on the new replacement switch. o The month and year of the initial installation written on switches that have been in service for less than four years. Recommendations The FAA recommends that owners, operators, and maintenance technicians do the actions of the above-referenced service bulletins within the next 400 hours of operation, 12 months, or the next annual inspection, whichever comes first. For Further Information Contact Daniel Hilton, Aerospace Engineer, FAA Wichita ACO, 1801 Airport Road, Room 100, Wichita, KS 67209, telephone: (316) 946-4173, fax: (316) 946-4107, e-mail: daniel.hilton@faa.gov.

Aircraft listed start with C120 and go to C340A