Docket No: FAA-2014-1058 

Directorate ID: 2014-SW-065-AD 

Originating Oftice Track ing No.: 

Disposition Comments 

Next Step: 181 FRAN D SNPRM 

0 These comments are in 

response to an SN PRM 

0 No Comments/Only Supportive Comments Received - Jfthis box is checked. no signatures are 

required. 

No Has the referenced service information been revised since the NPRM was issued? 

If yes, list latest revision and attach a copy. Note that changes beyond the scope of/he 

previously published NPRMwi/1 require a new notice. Contact the Directorate focal point 

for guidance. 1 ,th .. '-1 R\..' 1 ,jon 

Instructions: Summarize all comments by issue (not by commenter) and provide your recommended resolution of 

each issue. All comments relating to the same issue should be discussed together. Do not list all of the issues 

!Tom one commenter together. If changes to the AD are required based on the comments received, explain why and 

describe in detail what change(s) you recommend. Reference FAA-IR-M-8040. 1C Chapter 9 .. 

ISSUE 1: Select one of the following: applicability 

if other. explain: 

Commenter(s): Airbus Helicopters; Model AS365N3 does not have the referenced APM version or part 

number as the EC 155 B I helicopter. Further, the position estimation on the AS365N3 is implemented 

differently than on the EC 1558 I helicopter and the AS365N3 does not exhibit the same anomalous 

behavior as the EC l55B 1 discussed in this airworthiness directive. 

What change to the AD action is requested? AS365N3 should be removed from the applicability of th is 

AD. 

Why is the change requested or how is it justified? The AS365N3 and EC 155 B I incorporate different 

APM and position estimation with Garmin GPS is implemented differently between the two aircraft such 

that the anomalous behavior does not present itself on the AS365N3 aircraft. 

Do we agree? Yes 

Jf PARTIALLY AGREE, we agree with AS365N3 has different APM series and part number with 

different implementation of position estimation and will not exhibit the anomalous behavior 

described in this AD because this differentiation was not clearly understood at the time this AD 

was written. We disagree with \the need to remove the AS365N3 from the applicability because 

the applicability in this AD is tied to the APM series and part number, thus wou ld exclude any 

aircraft not equipped with the applicable items. Make the following changes to the AD: None 

lfNO, we don't agree because li."l'rllllll rLHio11:11~ 

ISSUE 2: Select one of the following: other 

if other, explain: Discussion section of AD 

Commenter(s): Airbus Helicopters; 

Page 1 of8 
What. change to the AD action is requested? The AD states ·'during initialization of the GPS, the Garmin 

GPS equipment declares the helicopter's position as invalid on the data output bus, even though the GPS 

correctly displays the position and other information." This is incorrect. The root cause is because during 

the test page display of the Gannin, the Garmin outputs a GPS location as Olathe, KS and identifies this 

position as valid (SSM Bit set to Normal Operation in the ARINC429 word). APM PN -163 uses 32 bit 

integer or floating point data (simple precision LEEE 754 format) to code positions on the earth. The APM 

SW samples a reference position expectantly not far from the current position and code the N/S and EIW 

position difTerences in floating point format, keeping the arithmetic practical. This relative position needs 

to be extrapolated between consecutive received positions and hybridized (3rd order and Ssec during 

initial phase and 30sec time constant during steady operations). Due to the limited physical memory space 

available, the integrators used in the -163 SW during the extrapolation stage is limited to+/- 1.000.000 

which corresponds to +/-1 OOOKm. Therefore the SW takes the initial aircraft position due to the EC 155 

range being smaller than I OOOKm or 540Nm. The reference position initialization is achieved in two steps 

- ( I) reference position sampling and (2) reference position locking. Starting from initial state where no 

position is yet sampled, a position is sampled when received valid >0.8sec then frozen. On the EC155 the 

only way position is received is from the Garmin GPS. Atler this freeze and if position is continually 

received as valid, hybridization initialization is maintained for 2.2sec and left runn ing for 30sec. If no 

validity has been lost during this time (total= 33sec) then the reference position is locked. If the validity 

is lost during this time for as little as lOOms then the whole process is repeated from the start. Once step 

(2) is locked it remains locked as long as the received position has not been received as invalid for at least 

60sec. >60sec received invalid position then the whole process is re-statted at step (I). Received valid is 

the SSM of bit of ARINC429 Label 310 and 311 set to Normal Operation (NO). Flight recordings 

accomplished in Gainesville, FL and Marignane, France revealed an initial position as Olathe, KS 

(> I OOOKm from aircraft) not the actual aircraft position. However the position was declared valid by the 

Garmin (SSM set to NO). When the Garmin correctly transmits the actual aircraft position and the delta 

between the two received positions is > lOOOKm as in this case, it saturates theN/S and EIW position 

calculations which causes the derived estimated ground speed to remain at 0. The ground speed estimated 

is taken to act as a damper on the inherent ILSNOR signal disturbances. Consequently when the 

estimated ground speed is at 0 this calculation cannot perfonn its dampening role. 

Why is the change requested or how is it justified? The change is requested to correct the technical details 

of how the anomalous behavior occurs in this GPS to Autopilot Module interface. 

Do we agree? Yes 

lfYES,weagreebecause hctt ~tlfkatl\ll\ Make the followingchangestotheAD: Ltsl<m; 

1 I 1l~;_\J) 

If PARTiALLY AGREE, we agree with the technical description in the AD is not correct because 

the provided technical descri ption cotTects that error. We disagree with the need to change the AD 

because the consequence of having the estimated ground speed calculated to 0 is tl1e final 

outcome, thus the result is unchanged. Make the following changes to the AD: None 

If NO, we don't agree because J 1 ~..·n l•Ur lt~ll )J\.lk· 

ISSUE 3: Select one of the following: Other 

If other. explain: Technical Discussion 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? The AD states Airbus "proposes in the interim that pilots, 

shortly before taxiing, confirm that the Garmin equipment is properly displaying the helicopter's true 

present position and then press the AP RST (autopilot reset)". This "interim solution'' is not entirely 

Page 2 of8 
correctly stated in the AD. The important step to mitigate the possibility of estimated ground speed being 

forced to 0 is by ensuring the erroneous data provided by the Garmin is not sent to the APM. Then as a 

second independent means to ensure this and in case the pilots over looked that step, AP RST is pressed. 

Why is the change requested or how is it justified? These two steps provide two independent means to 

ensure the APM receives correct true position and the reference position initialization phase starts and 

completes correctly. This was flight tested and recorded to show that this is in fact the case. The AD 

states " this condition is not CCD JTected by resetting the autopilot before taxiing. Rather, the issue continues 

until the autopilot system is manually disconnected." This is inconect. Airbus He licopters instrumented 

an aircraft in Florida and France and recorded the results of the procedure. That procedure was then 

inserted into the Flight Manual which the FAA subsequently approved and the revision was published 

October 17,2014. 

Do we agree? Partially Agree 

If YES, we agree because ln-....:1'1 Jll:o.tJiicatum Make the following changes to the AD: I 1st uu~ 

1lilli.:_:\:S IP till. \1) 

If PARTIALLY AGREE, we agree with the corrections to the technical discussion because the 

commenter provided clarifying information. We disagree with the position that the interim procedures 

adequately mitigate the unsafe condition because the FAA position is the procedures referenced in the 

mentioned flight manual supplement do not adequately ensure the pilot can have confidence that the G PS 

to autopilot is functioning correctly, prior to initiating a localizer or VOR approach. Make the following 

changes to the AD: None 

If NO, we don't agree because 

ISSUE 4: Select one of the following: Service Info 

If other. explain: Clict.. her~ lo l:llh:r t~xt. 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? AHTA AE-155- 14-003-22 was issued prior to validating the 

mitigating procedure now found in the approved Flight Manual. The procedure found in the latest revision 

of the FAA Approved Flight Manual is what was flight tested, recorded and verified with EASA. lt is also 

what the FAA has approved. 

Why is the change requested or how is it justified? Airbus Helicopter position is that this is the procedure 

that should be referenced in any communication. This is the only procedure which mitigates the noncompliance of the Garrnin GPS units and therefore allows correct LOC and VOR capture behavior. 

Do we agree? Partially Agree 

If YES, we agree because lns~rl justificallon Make the following changes to the AD: l isl an~ 

Lfl ngcs 10 the ;\1) 

If PARTIALLY AGREE, we agree with AHTA AE-155-14-003-22 having been issued prior to 

va lidating the mitigating procedure now found in the approved Flight Manual because The subject flight 

manual supplement revision was approved by EASA, on behalf of the FAA, in accordance with the FAAEASA validation procedure for flight manual revisions that do not affect the limitations section. A 

procedural anomaly occurred wherein the applicant sent this specific validation request to only one FAA 

individual, who happened to be out of the office for an extended period of time, instead of the usual 

multiple FAA individuals. Per the F AA-EASA validation procedure, after 2 1 days of no FAA response, 

EASA acted on the FAA's behalf and approved this supplement. Therefore, the FAA did not have 

Page 3 of8 
knowledge of the t1 ight manual revision until after it was approved by EASA on behalf of the FAA. 

Recommendations have been made for the applicant to re-instate the procedure of sending such requests 

for FAA review to multiple FAA recipients from this point forward. We disagree with the 

appropriateness of this procedure because after following the listed procedures, the pilot has no feedback 

indication the system is operating correctly, prior to attempting to intercept the localizer/ILS or VOR 

radial during the autopilot coupled instrument approach. Make the following changes to the AD: None 

If NO, we don't agree because llic:l~ her:: h' t.'nh:r h:xl 

ISSUE 5: Select one ofthejollowing: Other 

If other, explain: Interim Actions 

Commenter(s): Airbus He licopters 

What change to the AD action is requested? Airbus Helicopters is making a SW evolution to deal with 

the Gannin GPS units noncompliance with the ARINC429 Specification. The aircraft testing of the AP 

SW completed DEC 20 14. Qua lification and Design Declaration is currently at the vendor. Once 

completed, the certification package w ill be sent to EASA NL T JAN 31,2015. 

Why is the change requested or how is it justified? The FAA is aware of the effort by Airbus Helicopters 

to correct this anomalous behavior by way of a software update to the APM. Once that software has been 

certified and validated, the resulting APM part number will change, making this AD not applicable to 

aircraft that have been updated by approved software. 

Do we agree? Yes 

If YES, we agree because a means to con·ect the anomalous behavior is warranted, to remove the unsafe 

condition. Make the following changes to the AD: None. 

lfPARTIALLY AGREE, we agree with Insert t~x l because fn-.cr'ljlt'-lilicatitm Insert tc'<t because 

I ~~·rt il .,, f I tl j .. '!Make the following changes to the AD: r is! any ~:han!-!es t<' tht: J\ () 

If NO, we don't agree because lnSL'll ,)ur l'alil)J1ak 

ISSUE 6: Select one ojthefollowing: Other 

If other, explain: Unsafe Condition 

Commenter(s): Airbus He licopters 

What change to the AD action is requested? The AD states "This AD defines the unsafe condition as an 

autopilot software design that incorrectJy calculates the estimated ground speed at zero. This condition 

resu lts in unpredictable roll oscillations during a coupled Very High Frequency Omnidirectional Range 

(VOR) or Localizer/lnstrument Landing System (LOC/ILS) approach, wh ich could result in loss of 

helicopter control'·. The incorrect ground speed estimation only leads to roll rate (5 deg/s) and bank angle 

limited (0.225 times the air speed in kt with a maximum at 30 de g) roll motions, not " loss of helicopter 

control" as stated in the AD. Flight tests have confirmed that the crew actions involved in recovering the 

aircraft are we ll within the pilot capabilities and only result in a slight increase of pilot workload, such as 

routine flight plan change (for example a missed approach). Those consequences are in accordance with 

AC 29 subpart F, section AC 29.1309 EQUIPMENT, SYSTEMS, AND INSTALLATIONS, subsection 

b. Procedures, subsection (2) Definitions of Failure Condition Classifications, paragraph (ii) MINOR 

Page 4 of8 
··failure conditions which would not significantly reduce rotorcraft safety, and wh ich would involve crew 

actions that are well within their capabilities. 

Why is the change requested or how is it justified? Minor fai lure conditions may include, for example, a 

slight reduction in safety margins or functional capabilities, a slight increase in crew workload, such as, 

routine flight plan changes, or some physical discomfort to occupants" . This is why the MINOR 

classification has been retained for th is event. Furthermore, the application of the Flight Manual SUP 60 

procedure prevents the ground speed from being incorrectly estimated and hence ensures cotTect YOR 

and LOC modes operation. 

Do we agree? No 

If YES, we agree because lnscn justification Make the following changes to the AD: t.ist an) 

~..,1 u '="-: l~ th~ AD 

If PARTIALLY A G REE, we agree with lns~.rt lt:\t because lll'>UI 11 l 111....111 11 We disagree with 

rn-.~rt tc, l because ln-.crl lll"l ll l~o.a l!llll Maket efo ll owi gchan gestotheAD: I t 11 ~.1.~1; t 1.. 

'\I) 

If NO, we don't agree because the FAA determined during single pilot lFR operations, for which these 

aircraft are approved, a mitigating design feature is the requirement to have a properly functioning 

autopilot system. The anomalous behavior exhibited during coupled VOR/LOC/ILS instrument 

approaches under instrument meteorological conditions occurs during the typically high workload 

approach phase of flight, particularly for single pilot operations. The aircraft making flight course 

deviations due to the unexpected and unpredictable roll oscillations during this phase of flight can be 

expected to divert the single pilot's attention away from other critical tasks, creating an unsafe condition. 

ISSUE 7: Select one ofthefollowing: Costs 

If other, explain: C lh.:k ht:r~ ll1 cnh:r k 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? The AD states '"We estimate that this AD will affect 16 

helicopters of U.S. Registry .. . " Only he licopters fitted with -163 APM (EC ISS post MOD 22870; 

AS36SN3 post MOD 22B7S) and GNS400W installed are exposed. 

Why is the change requested or how is it justified? There are only five aircraft in the US registry which 

that configuration. 

Do we agree? Yes 

If YES, we agree because the number of helicopters was an estimate and based on including the 

AS36SN3 and possibly more EClSSB l helicopters coming into the US market. The financial impact on 

the US economy is not significantly changed with the difference in the number of affected aircraft. 

Make the following changes to the AD: None 

lf PARTIALLY AGREE, we agree with ln::.ert ll'\l because ln..;erl ju llli~..~u.lll We disagree with 

ln-.t..•n te\t because ]Jl<;t..'rl tllslilkathlllMake the following changes to the AD: I ''-' 'll' c 1.11 ~.-•, \..; 

t\J) 

If NO, we don't agree because Jn-,~n llUr ratiomtlc 

ISSUE 8: Select one of the following: Other 

Page 5 of8 
If other. explain: Com pi iance justification 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? Airbus Helicopters Inc requests from the FAA the rationale 

of why "performing the procedures in Paragraphs 4.2 and 4.3" is prohibited. Furthermore it is assumed 

that the reference in para (e) (2) is incomplete as there are many sections 4.2 and 4.3. 

Why is the change requested or how is it justified? As flight tested and recorded this procedure provides 

two independent means to prevent the erroneous but declared valid information by Gannin from 

occurnng. 

Do we agree? No 

If YES, we agree because lns..:rt j11sti fil':tll\10 Make the following changes to the AD: ( lu:~ ht:t\: 10 

l'fu l~ ' t 

lfPARTIALLY AGREE, we agree with ln..,~n le"'.l because In:-t:rl iustilic1.1tion We disagree with 

.... , t ll'\ 1 because lnsc:tl J 1 ISll fk•1111 mMake the following changes to the AD: I ist any dwngc" tu th~.· 

\ll 

If NO, we don't agree because the referenced steps 4.2 (Re-) Power-on GPS on Ground or in flight and 

4.3 Pre-taxiing checklist, in the RFMS SUP. 60 are prohibited because there is no indication, to the pilot, 

that either ofthese procedures successfully circumvented the issue, until capture of the ILS/LOC or VOR 

is attempted. With regard to the reference to AD paragraph (e) Required Actions, sub paragraph (2)(ii), 

the association with the sections 4.2 and 4.3 in the last sentence is in direct reference to the preceding 

sentence, wherein the title of those steps was provided, for c larity. Other than this comment, there have 

been no inquiries or questions on the intent or the reference portion of the RFMS. 

ISSUE 9: Select one o.fthe.following: Other 

lfother, explain: Request for FAA revaluation 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? Request the FAA flight test the procedure which has been 

validated by AH and EASA before making a detennination. 

Why is the change requested or how is it justified? In the event the pilot does not apply the updated RFM 

procedures for GNS-400 GPS and AFCS initialization, and the roll oscillations are present on LOC 

intercept, the situation is easily remedied by the pilot. The required action is; 1. Momentarily depress the 

force trim release 2. level the helicopter 3. Re intercept the localizer 4. Release the force trim release 5. 

Monitor and allow the coupled approach to continue 

Do we agree? No 

If YES, we agree because l1-;~r1 1 Lblilit:,ll iPn Make the following changes to t he AD: I isl <Ill\ 

I 'ill • ' lhl: \I) 

lf PARTIALLY AGREE, we agree with lll'L'I'1 1~\l because ln~tnju..;tilicalwt1 We disagree with 

·,.. 1 t~., '\ because In- 1 1 .l .111 H: t j, 11 Make the following changes to the AD: I ,tr.;l am dtallh-C" tn tho..· 

\I' 

Page 6 of8 
If NO, we don't agree because based on discussion with pilots that had experienced this anomalous 

behavior in flight, the FAA mght test group detennined during single pilot IFR operations a mitigating 

design feature is the requirement to have a properly functioning autopilot system. The anomalous 

behavior exhibited during COt)pled YOR/LOC/lLS instrument approaches under instrument 

meteorological conditions occurs during the typically high workload approach phase of flight, pa11icularly 

for single pilot operations. The aircraft making unexpected flight course deviations due to the unexpected 

and unpredictable roll oscillations during this phase of flight can be expected to divert the single pilot's 

attention away from other critical tasks, creating an unsafe condition. 

ISSUE 10: Select one ojthejollowing: Costs 

lj other, explain: Cli.ck here In 1:1H-.:r l!.:'\;1. . ' . 

Commenter(s): Airbus Helicopters 

What change to the AD action is requested? The proposed AD effectively limits the aircraft to DPIFR. 

Why is the change requested or how is it justified? Most operators are not staffed for DPlFR and 

therefore limited to SPY FR. The cost estimate does not capture the actual cost of adding pilots for DPIFR 

operations, potential lost revenue or the increase in emergency response time as EMS operators may not 

be able to execute airborne EMS operations. 

Do we agree? No 

If YES, we agree because lnsert .iustitkation Make the following changes to the AD: I 1,1 ::111\ 

changes to the AD 

lfPARTIALLY AGREE, we agree with Insert tc:-<1 because lnsen iustifi\:ation We disagree with 

ln-.er1 lc\1 because Tnsert iu~titication Make the following changes to the AD: l 1:-.t ·II\ ~..h<ill~c .. 1 rl t: 

\() 

If NO, we don't agree because The limitation imposed by this AD is a prohibition of autopilot coupled 

LOC/fLS or VOR approaches. Also, removing (and prohibiting) the RFMS SUP 60 Normal Procedure 

steps 4.2 (Power-on GPS on Ground or Flight) and 4.3 (Pre-taxiing checklist). There is no reference to 

limiting single pilot or requiring dual pilot operations for lFR :flight. The intent being there are a variety 

of other instrument approach procedures that are not affected by this anomalous behavior and would be 

available for single or dual pilot lFR operations. 

For additional issues, double-click here 

Page 7 of8 
Signature Section 

Signature indicates concurrence with this action. 

Originating Office Tracking No.: 2014-ASW-065-AD 

ASE ___ <f: --, p,;nted~eo,ge Schwab 

i -;?9-/6 

Date 

Page 8 of 8