FAA disposition of comments to FAA AD 2012-15-04:

Commenter 1 made three comments:

Comment 1: 

Comment on the FAA's Determination of an unsafe condition:

“The start of the roll oscillation in LOC mode at the end of an approach does not

lead to an unsafe condition.”

FAA Disposition:

The FAA made the determination that the autopilot behavior in the single-pilot IFR 

operations environment is a safety issue and rose the level of an unsafe condition based 

on flight evaluations involving both certification test pilots and a flight standards aircraft 

evaluation group operations pilot. Follow up analysis using the FAA monitor safety and 

analyze data process, showed that the autopilot behavior rose the level of an unsafe 

condition.

Comment 2:

Comment on AD requirements:

“Alternate ways to safely complete an approach below 500 ft than using the LOC

mode in 4-axis configuration have been extensively demonstrated in single pilot

IFR operation. Eurocopter agrees to increase the LOC mode Minimum Use

Height, in 4-axis configuration, from 200 ft to 500 ft over the US territory but

disagrees with the EC155 interdiction of single pilot for IFR operations.”

FAA certification requires the autopilot to perform its intended function throughout its 

operational envelope. For single pilot operations, particularly in commercial operations 

(14 CFR 135), an autopilot can be used in lieu of second-in-command for IFR operations. 

The autopilot in this case did not provide a stabilized approach on the final approach 

segment. Increasing the minimum use height (MUH) from 200 ft to 500 ft would not 

alleviate the requirement of the autopilot to be “. . . capable of operating the aircraft 

controls to maintain flight and maneuver it about the three axes; . . .”(14 CFR 135.105 

(c)(1)). Changing the MUH to 500 ft would not solve the issue but only restrict single 

pilot IFR to Part 91 operations. The FAA considered limiting the dual pilot IFR 

requirement to 14 CFR 135 operations only but that solution was not considered feasible 

since the behavior of the autopilot was not performing its intended function and was 

considered presenting an unsafe condition regardless of whether the aircraft was 

operating under general aviation rules (Part 91) or commercial operations (Part 135). 

Comment 3:

Comment on costs of compliance:

“The FAA AD strongly underestimates the Costs of Compliance because it does not

take into account the additional operator cost due to the 2nd pilot in IFR flight.”
The FAA only considers the direct cost for the actions mandated, ie parts and man-hours 

to perform inspection/replacement in accordance with FAA-IR-M-8040.1C, paragraph 

9.e. which states:

“Do not state any costs beyond initial work-hours and parts costs; that is, don’t 

include costs that operators might incur in individual maintenance scheduling or 

costs that operators might pass on to others.”

When the FAA was determining the cost of the AD to operators, the decision not to 

include the cost of adding a second pilot was considered and rejected. The investigation 

into the fleet of aircraft impacted by a dual-pilot IFR limitation revealed that there were 

six EC155B1 aircraft in the U. S. fleet. Three aircraft had, at the time the investigation 

was accomplished, not been delivered to their operator. Two of the aircraft were 

operated by commercial operators who did not have single-pilot IFR operational approval 

for operations under 14 CFR 135, and one aircraft operated by the aircraft manufacturer’s 

U.S. facility as a marketing demonstrator. Therefore, the economic impact for 

commercial operations at that time was negligible for the existing U.S. fleet. 

Additionally, the FAA did not include the cost of a second pilot since operators are not 

required to fly their aircraft IFR. 

The second commenter provided five comments to the AD. The format of the comments 

do not support inclusion verbatim in this response so they are paraphrased.

Comment 1 : The commenter stated they did not believe pilots would find themselves in 

“loss of control” situation given the behavior of the autopilot. The commenter also stated 

that they had no indication from other world-wide EC155B operators that the oscillations 

they experienced created concerns about additional workload or loss of control.

The autopilot oscillations and the point on the final approach segment where they

occurred, did not provide a stable approach platform. The FAA made the determination 

that the autopilot behavior in the single-pilot IFR operations environment is a safety issue 

and rose the level of an unsafe condition. This determination was based on flight 

evaluations involving both certification test pilots and a flight standards aircraft 

evaluation group operations pilot. Follow up analysis using the FAA monitor safety and 

analyze data process, showed that the autopilot behavior rose the level of an unsafe 

condition. The FAA was unaware that the there were other pilots in other countries 

experiencing the same issues. 

Comment 2: The commenter stated that if the FAA conclusion that an unsafe condition 

exists, the most stringent restriction should have been two pilots for ILS/LOC approaches 

planned to be flown in IMC and allow other approaches such as GPS, VOR, ADF 

approaches to be flown single pilot.
The FAA considered various iterations of limitations to mitigate the issue. The end result 

was that the FAA decided to issue the dual-pilot IFR limitation instead of operationally 

specific limitations because the dual pilot limitation did not limit where the aircraft could 

fly IFR vs. other limitations that limited where the aircraft could fly. Additionally, the 

FAA determined that the AD does not require operators to fly IFR and the decision to do 

so is their choice.

Comment 3: The commenter stated they had raised this issue a number of years ago. 

The FAA considers this a statement of fact.

Comment 4: The commenter raises the issue that the FAA underestimated the cost of 

implementing the AD because of the cost of installing a cockpit voice recorder required 

under 14 CFR 135. 

The FAA’s investigation revealed that there were no 14 CFR 135 operators flying 

EC155B1’s who had authorization to fly IFR or fly IFR using the autopilot in lieu of 

second in command. As a result, this cost was not considered since it did not apply to the 

current U.S. fleet.

Comment 5: The commenter stated that it was OK to fly single pilot IFR for the number 

of years since they brought the oscillation to the FAA and manufacturer’s attention but 

now immediate action is required.

Research into the oscillation issue revealed one service difficulty report on the EC155B 

autopilot system entered in 2005. There was no other previous documentation on the 

FAA’s part that this issue was reported through the FAA’s service difficulty reporting 

system.