FAA to raise the bar on helo certification rules

 - November 8, 2006, 7:54 AM

The FAA is about to change helicopter certification rules to align them with the current  performance levels of the aircraft they regulate. The rules, in effect, are catching up with the improved capabilities of modern rotorcraft.

The agency issued a notice of proposed rulemaking (NPRM) last August, and the comment period was to end on October 23.

The proposed changes affect Part 27 (normal category) and Part 29 (transport category) regulations. Part 27 applies to helicopters that weigh 7,000 pounds or less and have nine seats or fewer, up to the size of a Eurocopter EC 135 or Bell 429. Part 29 applies to larger helicopters, from the EC 145 or Bell 430 and up, for example.

In the NPRM the FAA acknowledged that some of the current regulations do not reflect safety levels attainable by modern rotorcraft. The agency believes that revised airworthiness rules will enhance the safety standards for performance and handling qualities.

As the FAA notes, “It had been more than 20 years since the last major promulgation of rules that address…performance and handling.” The issue has been under consideration since 1995, when the Performance and Handling Qualities Requirements Harmonization Working Group met for the first of thus far nine times. It included representatives from manufacturer associations, the FAA, Transport Canada and the European Joint Aviation Authorities (JAA)–which are being superseded by the European Aviation Safety Agency (EASA).

For example, the proposed change revises one Part 27 rule to recognize that the most critical center of gravity is not necessarily the extreme forward c.g. The new rule  requires tests at the most critical c.g. configuration and mtow.

The proposed rule also requires in-flight engine restart capability to help minimize the risk of a forced landing. The agency admits that this capability will be useless in some cases, such as when there is engine damage or the helicopter is at too low an altitude.

Another paragraph allows a minimal amount of neutral or negative stability around trim, but it does not allow irregularity in the way the aircraft responds to control inputs. The proposed paragraph also requires that the pilot be able to maintain heading without exceptional skill or alertness, the agency says.

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

In addition, the proposed change rewrites portions of Part 27 and 29 to state more clearly that controllability on or near the ground must be demonstrated throughout a speed range of at least zero to 17 knots. The FAA said that some applicants could conclude from current rules that only a 17-knot controllability data point must be considered.

Another change to Part 27 mandates that controllability be determined at altitudes above 7,000 feet (density altitude) if takeoff and landing are scheduled above that altitude. There is currently no requirement for this. The FAA said it is adding that regulation because today’s lighter and more powerful engines make it possible for rotorcraft to operate at altitudes previously limited to just a few machines performing specialized operations.

No Autopilot Requirement
Although the working group discussed autopilots extensively, the FAA has not
included them in its proposed rulemaking. The agency did, however, consider modifying the Appendix B, IFR flight characteristic requirements.

The agency decided not to initiate Part 27 and 29 rulemaking on autopilots because of the complexity and variability of the systems, a dramatic change from the older analog systems. The agency said that it would handle the certification requirements for these systems case by case within the current regulatory structure “due to the difficulty of adequately addressing all the various elements of these systems and the associated flight characteristics.”

The total estimated cost of the proposed rule is $558,000 over the next 10 years, a cost the agency has deemed not prohibitive for small businesses. The FAA attributes the low cost to the fact that most helicopters already comply with the proposed rule. The agency estimates that the benefit (the value of lives and property saved by avoiding one accident) of the proposed rule would be at least $3.9 million over 10 years.

Manufacturers had submitted no comments at press time. Eurocopter told AIN only that it supports the NPRM. In one of only two official comments posted on the FAA’s Web site as this was written last month, Erickson Air-Crane commented that it agrees with the proposed rule. Bell would not comment. AgustaWestland and Sikorsky did not respond to requests for comment.

June 2017
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