FAA raising the bar on helicopter certification

 - March 19, 2007, 8:25 AM

The FAA’s plans to update certification rules to reflect the improved capabilities and performance of modern helicopters appears to be moving ahead with few hurdles, according to officials with knowledge of the changes proposed last August.

The FAA’s notice of proposed rulemaking on the subject affects newly manufactured Part 27 (normal category) and Part 29 (transport category) rotorcraft. Part 27 applies to helicopters weighing 7,000 pounds or less and with nine seats or fewer, up to the size of a Eurocopter EC 135 or Bell 429. Part 29 applies to larger helicopters, from the size of the EC 145 or Bell 430 up to Bell’s BA609 tiltrotor.

Some of the current regulations do not reflect safety and technological improvements that have been applied in modern rotorcraft. Such advances combined with changes in the way new helicopters are operated prompted the FAA to propose the revised airworthiness standards, which it believes will lead to enhancements in safety, performance and handling qualities.

“It had been more than 20 years since the last major promulgation of rules that address…performance and handling,” the FAA noted in its proposed rule. The issue had been tackled as early as 1995, when the FAA’s so-called Performance and Handling Qualities Requirements Harmonization Working Group met for the first time. The group has since met nine more times and grown to include representatives from manufacturer associations, the FAA, Transport Canada and the European Joint Aviation Authorities (JAA)–the latter which is being superseded by the European Aviation Safety Agency.

The rule changes cover a wide variety of operational and engineering considerations. For example, one of the Part 27 rules would be revised to recognize that the most critical center of gravity (c.g.) is not necessarily the extreme forward c.g., but instead requires testing in critical c.g. configurations and at maximum takeoff weight.

A paragraph is also being added to require in-flight engine restart capability. Another paragraph imposes a minimal amount of neutral or negative stability around trim and does not allow irregularities in response to control input. The proposed paragraph also requires that the pilot be able to maintain heading “without exceptional skill or alertness.”

Moreover, the FAA wants to update Part 27 rules concerning out-of-ground-effect (OGE) hover performance. It noted that installed engine power has increased significantly since the promulgation of the original Part 27 requirement, particularly for hot-and-high conditions. As a result, OGE helicopter missions once limited to special missions have become commonplace. The change would require that OGE hover data be determined throughout the range of weights, altitudes and temperatures.

In both the Part 27 and 29 revisions, paragraphs are rewritten to more clearly state that controllability on or near the ground must be demonstrated from zero to 17 knots, at least.

Also new, under the revised Part 27 certification rules, controllability must be determined at altitudes above 7,000 feet (density altitude) if takeoffs and landings are to be performed above that altitude. Since more rotorcraft now can operate safely at these altitudes, safety dictates that controllability and maneuverability be determined above 7,000 feet, the FAA asserted.