The US Federal Aviation Administration has agreed to review the metrics for determining certification standards for civil helicopters in the wake of a potentially damaging decision on an exemption request for the Bell 429.

Seeking to improve the Bell 429's market base, Bell Helicopter Canada earlier this year requested an exemption from the part 27 standard that would allow the airframer to increase the maximum take-off weight by 226kg, raising the limit to 3,400kg (7,500lb).

Increasing the weight would remove one of the key drawbacks for the Bell 429 in the market. It is unable to carry eight passengers and a full load of fuel within the part 27 limit, unless the operator removes several systems necessary for using instrument flight rules.

If the FAA allowed the exemption, the Bell 429 would avoid a costly re-certification process under the stricter part 29 standard and increase its sales projection by 350 aircraft over the next five years.

But the FAA decided it could not approve Bell's request for an exemption from the part 27 standard. In a 13 August ruling, the agency reminds Bell's management that they decided to certify the Bell 429 at the less stringent standard by keeping its maximum weight slightly below the 3,170kg threshold.

"The relief sought would, if granted, put existing part 29 rotorcraft manufacturers at a competitive disadvantage owing to the greater costs to certify and produce their products," the FAA says.

But the FAA has also agreed to review whether the take-off weight standard for part 27 aircraft should be updated. Agency officials have promised to consider whether the parameters, including maximum weight and number of passenger seats, should be changed, or if other criteria should be used for setting standards for airworthiness certification.

Source: Flight International