In The Works: How do special conditions work?
Whenever the non-aviation media gets hold of a story that involves aircraft certification issues, such as the recent Boeing 787 lithium-ion battery problems, an enterprising reporter “discovers” that the FAA applied “special conditions” to the certification of the product in question. These stories seem to imply that the manufacturer was given some sort of special dispensation, a way to get around the regulations to obtain the FAA’s stamp of approval.
But that isn’t how special conditions work. FAA regulations can’t cover every possible way of designing aircraft or new technologies. And crafting new regulations is a lengthy, years-long process. So when aircraft designers want to do something different, such as building structure with composite materials, adopting fly-by-wire flight controls or adding a lithium-ion battery, the FAA may impose special conditions that accommodate the new technology.
Special conditions are regulatory but apply to a specific design, according to 14 CFR 11.19, which covers general rulemaking procedures: “The FAA issues special conditions when it finds that the airworthiness regulations for an aircraft, aircraft engine or propeller design do not contain adequate or appropriate safety standards, because of a novel or unusual design feature.”
The process for issuance of special conditions begins with the manufacturer telling the FAA what is needed, according to an FAA spokeswoman. “If we don’t have rules, we ask, ‘What do we need to do to address this?’ Then we put together the requirements.”
As with most certification processes, once the special conditions are established, it’s up to the manufacturer to figure out how to accomplish tests and write documentation that proves that the special conditions can be met. The FAA does no testing but validates the testing done by the manufacturer.
Fans of aircraft design can learn a lot by reading special conditions, and the FAA makes them easy to find, in the Regulatory and Guidance Library (rgl.faa.gov), along with other interesting certification information such as exemptions, equivalent levels of safety determinations and much more.
Looking through special conditions documents, one can often glean information that manufacturers are reluctant to release, usually for marketing reasons, early in a program. This might include weights and technology details such as plans to use lithium-ion batteries. A Jan. 6, 2005, special conditions document revealed Cessna’s plans to develop a diesel-powered Cessna 172. Cessna canceled that program just before its engine vendor–Thielert–went bankrupt, so the diesel 172 remains an oddity in the aftermarket modification market. Special conditions also reveal that Gulfstream initially named the G650 the GVI; that moniker is forever enshrined in FAA documents (and in the band Far East Movement’s catchy tune “Like a G6”).
Special conditions aren’t guaranteed to prevent problems. They applied, for example, to lithium-ion main-ship battery installations in the Cessna Citation CJ4 and Boeing 787, but no regulation can anticipate all outcomes, and somehow one battery in a CJ4 and two batteries in 787s overheated.