Circuit Breaker AD Final Rule — -Updated with links to applicable Service Bulletins

Switch-type Circuit Breaker Airworthiness Directive

Airworthiness Directive 2008-13-17 requires certain circuit breaker-type switches be replaced in F33, F33A, G33, V35B, A36, A36TC, B36TC, B55, D55, E55, A56TC, 58, 58P, 58TC and G58 airplanes.  Model 77 Skippers are also affected by this AD. 

See the AD 2008-13-17 for airplane serial number effectivity. 

ABS is very disappointed that FAA held a firm line on this costly and onerous rule when all evidence is that the problem is extremely rare, and even the defective circuit breakers involved in supportive testing were detected and removed from service using existing industry techniques.

NPRM Comments

ABS commented in detail on this issue when it was published a Notice of Proposed Rulemaking (NPRM) in 2007.  AOPA and several private individuals commented on the NPRM as well.  ABS’ extensively researched and documented comments found that:

• There is no imminent threat to aircraft occupants or the public.

• Those very few reports affect only high electrical-load items, and only in Model 58 Barons.

• Testing by Raytheon Aircraft (now Hawker Beechcraft) and FAA does not indicate a wider threat of failure.

• High-utilization fleet service has shown there is no significant threat of switch overheat.

• An equivalent, even improved, level of safety would result from education in lieu of regulation.

• There is a critical shortage of replacement switches.

• Operational history of these switches does not warrant an $18 million impact on airplane owners.

For figures, tables and details supporting each of these statements read ABS’ 2007 comments to the NPRM.  AOPA’s NPRM comments are also posted on the ABS website.

FAA Response

In its AD Final Rule FAA has addressed and dismissed each of ABS’ comments, and the comments of AOPA and others.  FAA does state that:

"Hawker Beechcraft has assured us that the replacement parts are either available or could be manufactured within the 12-month compliance time. If there becomes a shortage of parts, we would consider extending the compliance time following the AMOC procedures outlined in 14 CFR 39.19 and this AD."

In response to every point FAA concludes: “We are not changing the final rule AD action based on these comments.”

Several calls to Hawker Beechcraft and RAPID found there is no knowledge of this impending AD in the circuit breaker supply chain.  The head of RAPID has promised to investigate its plans for meeting the demand for new breakers, and to let ABS know his findings promptly.

Cost of compliance

FAA now estimates the potential cost of compliance to be even higher than the $18 million impact ABS estimated from its research.  According to the AD the overall cost of compliance is $185 per circuit breaker, with a total estimated fleet impact of over $2 million if each affected airplane needs one replacement circuit breaker, to over $30 million to replace 15 such breakers per airplane.  To be fair, most affected airplanes do not have 15 switch-type circuit breakers, although some Barons have more than 15.

Compliance requirements

From the AD:

"This AD applies to airplanes that have a part number (P/N) 35-380132-1 through 35-380132-53 circuit breaker toggle switch installed.  This AD results from reports of certain circuit breaker toggle switches used in various electrical systems through the affected airplanes overheating. We are proposing this AD to prevent failure of the circuit breaker toggle switch, which could result in smoke in the cockpit and the inability to turn off the switch." 

The AD became effective 35 days after July 2nd publication in the Federal Register (August 6, 2008).  Airplane owners will have 12 months after that date to replace all (P/N) 35-380132-1 through 35-380132-53 circuit breaker-type switches with new-design switches purchased from Hawker Beechcraft. 

For more information see AD 2008-13-17 for specific requirements.  The AD requires compliance with Hawker Beechcraft recommended service bulletins SB 24-3735 (all affected models except G58) and SB 24-3807 (G58 Barons only).

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