This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

6835 

Vol. 74, No. 27 

Wednesday, February 11, 2009 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2006–24587; Directorate 

Identifier 2006–SW–05–AD] 

RIN 2120–AA64 

Airworthiness Directives; Sikorsky 

Aircraft Corporation Model S–76A, B, 

and C Helicopters 

AGENCY: Federal Aviation 

Administration, DOT. 

ACTION: Supplemental notice of 

proposed rulemaking; reopening of 

comment period. 

SUMMARY: This document revises an 

earlier proposed airworthiness directive 

(AD) for Sikorsky Aircraft Corporation 

(Sikorsky) Model S–76A, B, and C 

helicopters. That AD proposed to 

require inspecting each installed HR 

Textron main rotor servo actuator (servo 

actuator) for a high rate of leakage and 

for contaminated hydraulic fluid and 

reducing the time-in-service (TIS) 

interval for overhauling each servo 

actuator. That proposal was prompted 

by a National Transportation Safety 

Board (NTSB) Safety Recommendation 

issued in response to an accident 

involving a Model S–76 helicopter. In 

the NTSB Recommendation, the 

performance of an HR Textron servo 

actuator was questioned as a result of 

piston head seal leakage and piston 

head plasma spray flaking. Since the 

issuance of the initial proposal, and 

based on further information obtained 

from the accident investigation, the 

comments to the proposal, and other 

test and service history data since we 

issued the initial proposal, we continue 

to believe that servo actuator pistons 

may experience piston head seal leakage 

and plasma spray flaking, but have 

determined that the full scope of the 

initial proposal is unnecessary. We 

believe that the piston head seal leakage 

and plasma spray flaking can be 

addressed by leakage rate inspections 

and replacement of the current servo 

actuator pistons with an improved 

design not as susceptible to plasma 

spray flaking. Therefore, we are revising 

the proposed rule by removing the 

requirement to inspect the hydraulic 

fluid for contamination; removing the 

requirement to reduce the interval for 

overhauling an affected servo actuator 

from 3,000 to 2,000 hours TIS; revising 

the initial inspection time; and 

removing the 600 hours TIS repetitive 

hydraulic fluid leak inspection. We are 

proposing to add a 2,250 hours TIS 

hydraulic fluid leakage inspection and 

to add a requirement to either install a 

new design servo actuator or replace the 

servo actuator pistons when there is 

excessive leakage or upon reaching a 

certain time interval. These actions are 

intended to prevent degraded servo 

actuator performance as a result of 

piston head seal leaking and plasma 

spray flaking, which could result in 

subsequent loss of control of the 

helicopter. 

DATES: Comments must be received on 

or before April 13, 2009. 

ADDRESSES: Use one of the following 

addresses to submit comments on this 

proposed AD: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: 202–493–2251. 

• Mail: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590. 

• Hand Delivery: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590, between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. 

You may get the service information 

identified in this proposed AD from 

Sikorsky Aircraft Corporation, Attn: 

Manager, Commercial Technical 

Support, 6900 Main Street, Stratford, 

Connecticut, phone (203) 383–4866, 

email address tsslibrary@sikorsky.com, 

or at http://www.sikorsky.com. 

FOR FURTHER INFORMATION CONTACT: 

Terry Fahr, Aviation Safety Engineer, 

Boston Aircraft Certification Office, 12 

New England Executive Park, 

Burlington, MA 01803, telephone (781) 

238–7155, fax (781) 238–7170. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to submit any written 

data, views, or arguments regarding this 

proposed AD. Send your comments to 

the address listed under the caption 

ADDRESSES. Include the docket number 

‘‘FAA–2006–24587, Directorate 

Identifier 2006–SW–05–AD’’ at the 

beginning of your comments. We 

specifically invite comments on the 

overall regulatory, economic, 

environmental, and energy aspects of 

the proposed AD. We will consider all 

comments received by the closing date 

and may amend the proposed AD in 

light of those comments. 

We will post all comments we 

receive, without change, to http:// 

www.regulations.gov, including any 

personal information you provide. We 

will also post a report summarizing each 

substantive verbal contact with FAA 

personnel concerning this proposed 

rulemaking. Using the search function 

of our docket Web site, you can find and 

read the comments to any of our 

dockets, including the name of the 

individual who sent or signed the 

comment. You may review the DOT’s 

complete Privacy Act Statement in the 

Federal Register published on April 11, 

2000 (65 FR 19477–78). 

Examining the Docket 

You may examine the AD docket, 

which contains the proposed AD, any 

comments, and other information, on 

the Internet at http:// 

www.regulations.gov or in person at the 

Docket Operations Office between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. The 

street address for the Docket Operations 

office (telephone (800) 647–5527) is in 

the ADDRESSES section. Comments will 

be available in the AD docket shortly 

after receipt. 

Discussion 

A proposal to amend 14 CFR part 39 

to add an AD for Sikorsky Model S– 

76A, B, and C helicopters with HR 

Textron servo actuators, part number 

(P/N) 76650–09805, installed, was 

published in the Federal Register on 

May 2, 2006 (71 FR 25783). That notice 

of proposed rulemaking (NPRM) 

incorrectly referenced the ‘‘HR Textron 

servo actuator, P/N 76650–09805.’’ It 

should have stated ‘‘servo actuator, 

Sikorsky P/N 76650–09805 (HR Textron 

P/N 3006760).’’ That NPRM proposed to 


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6836 Federal Register / Vol. 74, No. 27 / Wednesday, February 11, 2009 / Proposed Rules 

require, within 25 hours TIS, and 

thereafter at intervals not to exceed 600 

hours TIS, determining the leakage rate 

for each of the three installed servo 

actuators by installing a test line in each 

servo actuator return port and turning 

on the hydraulic power. If the leakage 

rate exceeded 700 cc per minute in any 

servo actuator, we proposed to require 

replacing that servo actuator with an 

airworthy servo actuator before further 

flight. That proposed AD would have 

also required inspecting the hydraulic 

fluid for contamination using a patch 

test kit or an independent laboratory 

analysis method. If the inspection 

indicated that the hydraulic fluid was 

contaminated, the proposed AD would 

have required flushing and refilling the 

hydraulic system with uncontaminated 

hydraulic fluid before further flight. The 

proposed AD also would have required 

reducing the TIS interval for 

overhauling an affected servo actuator 

from 3,000 to 2,000 hours TIS. 

Since issuing that NPRM, we have 

received comments from 10 

commenters, including two separate 

comments from the manufacturer, and a 

comment from the NTSB. We have 

reviewed the comments on that 

proposed rule and further analyses and 

test data. 

Seven commenters recommended that 

the NPRM be withdrawn. Another 

commenter recommended that no AD be 

published ‘‘until the FAA is absolutely 

certain that existing manufacturer’s 

maintenance criteria were performed by 

experienced technicians.’’ 

One of these commenters, Air 

Logistics, states several reasons why the 

NPRM should be withdrawn. First, they 

cite their 30 years of operational 

experience with Sikorsky helicopters, 

during which they had not experienced 

any servo failures. Second, they state 

that the results of Sikorsky testing 

indicates that servo actuators with 

leakage rates as high as 3000 cc per 

minute in one stage had the capacity to 

perform the entire mission spectrum. 

Third, they have conducted their own 

internal leak tests and hydraulic oil 

analyses and no defects or 

contaminations were found. Fourth, 

they state there is ‘‘no evidence’’ 

presented by the NTSB or FAA to justify 

the NPRM. Finally, they state that the 

1,000 hour TIS reduction would impose 

thousands of dollars of unnecessary 

expense without improving safety. 

Another commenter, Sikorsky Aircraft 

Corporation, states that the NPRM 

should be withdrawn for several 

reasons. First, they state that the scope 

of the NPRM is without authority 

because there is no unsafe condition 

and the NPRM is based on an NTSB 

recommendation founded upon 

‘‘preliminary speculation’’ regarding the 

root cause of an aircraft mishap that has 

been shown by testing and analysis to 

be without merit. Second, they state that 

they have 28 years and 9 million servo 

actuator flight hours, operational 

testing, materials analysis, and 

assessments of servo actuator operation 

within the fleet with no related 

operational problems. Third, they state 

that the existing maintenance program 

is adequate to assure safe, airworthy 

operation of the hydraulic system and 

its associated hardware, ‘‘including the 

main rotor servo actuator, within the 

current defined overhaul intervals based 

on operator data.’’ ‘‘This servo design 

has performed for over 25 years with no 

service anomalies.’’ Fourth, they cite 

‘‘extensive laboratory testing’’ 

conducted by them demonstrating that 

‘‘normal servo control is maintained 

throughout the certified flight envelope, 

even with leakage and wear particle 

conditions up to three times the 

[Sikorsky S76] Maintenance Manual 

limits’’, and state that the ‘‘servo 

actuator is airworthy for the entire 

certificated flight envelope even with 

significant fluid contamination and 

internal leakage, while operating on one 

stage only.’’ Fifth, they state that 

implementing the AD would create an 

unnecessary maintenance burden on the 

operators and increase fleet operating 

costs while providing no benefit. 

Additionally, the commenter provided 

several additional ‘‘Specific 

Comments’’. These specific comments 

further argue the contention that (1) 

performance of the servo is 

compromised by internal leakage and 

plasma spray flaking is incorrect; (2) 

servo internal leakage and hydraulic 

fluid contamination from flaking spray 

could result in loss of control of the 

aircraft is incorrect; (3) more frequent 

leakage tests are required to maintain 

servo airworthiness is unfounded; (4) 

more frequent hydraulic fluid 

cleanliness inspections are 

unwarranted; and (5) reducing the servo 

overhaul interval is unnecessary. 

Another commenter, Carl Violette, 

states that the NPRM should be 

withdrawn for several reasons. First, he 

cites his experience of 25 years and 

60,000 flight hours of maintaining 

accident-free operations of the Model 

‘‘S–76 variants.’’ Second, he states that 

overhauling all three Model S–76 servo 

actuators 1,000 hours TIS early when 

the leakage rates are so low is 

‘‘ludicrous.’’ Third, he states that the 

600 hour TIS inspection interval 

‘‘doesn’t make sense’’ considering the 

existing 100 hour TIS inspection. 

Fourth, he states that performing 

contamination inspections on the 

aircraft is ‘‘pointless’’ since the fluid is 

usually supplied by the hydraulic mule, 

which has a finer filter than the aircraft 

one, and therefore one would only find 

filtered hydraulic fluid in the aircraft. 

Fifth, he states that the NPRM will 

increase helicopter operating costs from 

$15 per hour to $22.50 per hour, and 

will cost their company an additional 

$9,000 per year without any failed servo 

actuators. Sixth, he states that the servo 

actuator ‘‘jump’’ check performed by the 

pilot each time the aircraft is started is 

a ‘‘better check’’ and would inform the 

pilots if there were any issues with the 

servo actuators. Seventh, he states that 

there is ‘‘no way’’ that the servo actuator 

could extend beyond the pilot’s inputs 

without a mechanical breakage 

somewhere, and that minuscule flakes 

won’t prevent the 3,000 PSI fluid from 

going where it wants to go. Eighth, Mr. 

Violette commented that he found it 

‘‘cavalier’’ that so little research was 

done on this proposal in light of the 

seriousness of the incident. He 

questioned the proposed frequency of 

the leakage checks, and why this 

leakage prompts us to lower the 

overhaul interval. He further stated that 

if contamination checks are required, 

then more guidance is required. He 

stated, ‘‘If a patch test is done, what is 

the accept/reject criteria? Can I send 

fluid to a lab instead? What are their 

accept/reject criteria? When should I 

replace a servo?’’ He stated that he 

doesn’t understand how the proposed 

AD makes the aircraft safer. 

Another commenter, Helicopter 

Support, Inc., states that the NPRM 

should be withdrawn for several 

reasons. First, in 20 years of overhaul 

and repair experience, they found 

flaking of the Model S–76 servo actuator 

piston plasma spray in only extremely 

rare circumstances. Second, Sikorsky 

testing showed ‘‘no connection between 

internal leakage of the main rotor servo 

actuator and subsequent loss of control 

of the helicopter.’’ Third, a reduction in 

the overhaul interval from 3,000 to 

2,000 hours TIS would impose an 

unnecessary financial burden, and 

would increase maintenance costs and 

negatively impact flight availability. 

Fourth, the maintenance procedures 

called out in Chapters 5 & 29 of the 

Sikorsky S–76 Maintenance Manual 

‘‘are sufficient to identify leakage and 

contamination’’ in the servo actuator 

system. Fifth, performing the leakage 

rate check is subjective and can lead to 

costly false removals of the servo 

actuator. Sixth, the 600 hours TIS patch 

test can be addressed by the 12 month 


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Federal Register / Vol. 74, No. 27 / Wednesday, February 11, 2009 / Proposed Rules 6837 

patch test requirement in the Sikorsky 

S–76 Maintenance Manual. 

Another commenter, Aero Med 

Spectrum Health, cited their 14 or more 

years of operating both Model S–76A 

and Model S–76B helicopters without 

any operational problems or internal 

failures of the servo actuators, or 

anomalies reported by the crew, as 

evidence that the AD is unnecessary. 

Another commenter, HR Textron, 

stated that the AD is unnecessary 

because the NPRM is based on 

‘‘speculation of an NTSB investigator’’ 

with respect to a Model S–76 helicopter 

accident that has been shown to be 

‘‘without substance or merit,’’ and 

extensive testing by HR Textron and 

Sikorsky have demonstrated that 

‘‘internal leakage and/or plasma spray 

flaking do not create an unsafe 

condition.’’ Further, information on the 

flight data recorder of the accident 

helicopter ‘‘do not support the theory 

that a mechanical malfunction of the 

servo caused the mishap.’’ 

Another commenter, Jay Deering, feels 

that the AD is ‘‘unnecessary’’ and will 

cause undue hardship for the operator. 

Another commenter, Steve Strollo, 

states that the ‘‘AD should not be 

published until the FAA is absolutely 

certain that existing manufacturer’s 

maintenance criteria were performed by 

experienced technicians.’’ He further 

states that in his 26 years as an A&P 

mechanic, he has seen only one serious 

servo actuator failure due to ‘‘tissue thin 

wall thickness along the entire length of 

the tube’’ and the pilots were unaware 

of the malfunction. He has never 

experienced excessive contamination of 

a hydraulic system, or a failed patch 

test. Also, he believes that degradation 

of the accident servo ‘‘did not occur 

overnight’’ and that if the 300 hours TIS 

inspection is performed correctly, 

damage to the servo actuator can be 

easily spotted. 

Regarding Mr. Strollo’s comment 

referencing the 300 hours TIS 

inspection, that is an inspection 

pertaining to ‘‘noticeable wear of the 

chrome plating on the visible surface’’ 

of the servo actuator piston that is not 

required by an AD and is not relevant 

to this proposal. 

Two commenters, Copterline Oy 

(Copterline) and the NTSB, supported 

the NPRM. 

One commenter, Copterline, was the 

operator of the Sikorsky Model S–76 

helicopter that crashed shortly after 

taking off in Estonia in 2005 and 

prompted the NTSB safety 

recommendation. Copterline states that 

the NPRM should be adopted in its 

entirety and expanded to include other 

servo actuators in which there is ‘‘a 

possibility for manufacturing process 

error’’ which can cause plasma coating 

to delaminate and block the servo 

actuator return ports, leading to loss of 

control of the helicopter. They state that 

‘‘the reason why the Plasma coating 

flakes off remains unaddressed.’’ They 

state that the NPRM should be 

expanded to include additional 

testing—for example, x-ray, ultrasonic, 

or other appropriate testing—to confirm 

that the plasma coating has adhered to 

the servo actuator pistons, which will 

further reduce risk. This commenter 

states that the NPRM should be more 

comprehensive. Copterline also states 

that the NPRM should propose a 

reduction in the servo actuator piston 

life limit until the plasma spray flaking 

problem has been resolved. Copterline 

cites NTSB laboratory findings and 

states that it agrees with Sikorsky that 

when one of the two return flow ports 

is blocked, safe operations can be 

conducted. However, if both return 

ports of the control valve have been 

blocked, the bypass function is not 

available and the blocked side will jam 

the other stage. They state that the 

‘‘laboratory testing results justify the 

NTSB’s concern.’’ Copterline also states 

that the proposed AD actions and even 

the additional requirements that they 

propose ‘‘would not adversely affect the 

S–76 operators and, in practise, [sic] 

would not materially increase operating 

costs of the S–76 fleet.’’ This commenter 

also states that continued accidents 

would be reflected in increased 

insurance premiums that would more 

than offset any short term savings 

associated with not taking appropriate 

action. 

Additionally, this commenter 

attached a copy of its ‘‘Detailed 

Comments to Sikorsky’s Comments on 

FAA and AOL’’ Web sites. These 

comments are consistent with those 

made to the NPRM. 

Another commenter, the NTSB, also 

supports the NPRM, and states that 

‘‘results of the Safety Board and 

Sikorsky tests demonstrate the need for 

issuance of a final rule consistent with 

the proposed AD as soon as possible.’’ 

Based on the comments summarized 

previously and our re-evaluation of the 

published proposal, we agree with 

various portions of the comments 

proposing withdrawal of the NPRM and 

portions of those supporting the NPRM. 

With respect to those comments citing 

operational experience, lack of 

supportive evidence by the FAA or 

NTSB, testing results, adequacy of 

existing maintenance programs, 

imposition of costly procedures without 

an increase in safety, and 

inappropriateness of the proposed 

procedures as evidence supporting 

withdrawal, we have determined that 

portions of the initial proposal are 

unnecessary to correct the unsafe 

condition, although there is still 

uncertainty about the root cause of the 

accident. Based on our reevaluation, we 

continue to believe that servo actuator 

pistons may experience piston head seal 

leakage and plasma spray flaking, but 

this does not justify the full scope of the 

initial proposal. We believe that the 

piston head seal leakage and plasma 

spray flaking can be addressed 

adequately by leakage rate inspections 

and replacement of the current servo 

actuator pistons with an improved 

design not as susceptible to plasma 

spray flaking. The reduction in the 

overhaul interval from 3,000 to 2,000 

hours TIS is not necessary if the leakage 

rate inspection is performed, and the 

leakage rate inspection is a better way 

of determining servo actuator condition 

than the hydraulic fluid patch test. 

Therefore, in order to prevent degraded 

servo actuator performance as a result of 

piston head seal leaking and plasma 

spray flaking, which may result in 

subsequent loss of control of the 

helicopter, we are revising the proposed 

rule by removing the requirement to 

inspect the hydraulic fluid for 

contamination using a patch test kit or 

an independent laboratory analysis 

method; removing the requirement to 

reduce the interval for overhauling an 

affected servo actuator from 3,000 to 

2,000 hours TIS; revising the initial 

inspection time; and removing the 600 

hours TIS repetitive hydraulic fluid leak 

inspection. We are proposing to add a 

2,250 hours TIS hydraulic fluid leakage 

inspection to the currently required 

1,500 hours TIS hydraulic fluid leakage 

inspection; and proposing to add a 

requirement to either install a new 

design servo actuator, Sikorsky part 

number (P/N) 76650–09805–111 (HR 

Textron P/N 3006760–111), or replace 

the servo actuator pistons, P/N 

41004321 with P/N 41012001 or P/N 

41012001–001, in servo actuators, 

Sikorsky P/N 76650–09805–109 and 

–110 (HR Textron P/N 3006760–109 and 

–110), either because of excessive 

leakage at the 1,500 or 2,250 hours TIS 

leakage inspection, or upon reaching the 

3,000 hours TSN or TSO maintenance 

interval. 

Regarding the comments in 

opposition to our proposal because of 

the cost, we agree that the initial 

proposal and these revised proposals 

would increase the operator’s 

maintenance costs. While the total 

estimated cost amount of the impact 

contained in the economic evaluation in 


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6838 Federal Register / Vol. 74, No. 27 / Wednesday, February 11, 2009 / Proposed Rules 

this SNPRM is larger than that 

contained in the previous NPRM, those 

cost amounts are only estimates based 

on different assumptions that are 

difficult to project. We believe that the 

reduction in the proposed requirements 

in this SNPRM will result in an overall 

lesser adverse economic impact on 

operators. Economic consideration is 

not and cannot be the paramount 

consideration in AD actions. The overall 

safety benefits must be considered. ADs 

are issued to correct unsafe conditions, 

and to return the type certificate to the 

approved minimum level of safety. 

Since we believe that the proposed 

leakage rate check and incorporation of 

the new servo actuator piston design are 

sufficient to address degraded servo 

actuator performance as a result of 

piston head seal leakage and plasma 

spray flaking, Copterline’s proposed 

additional x-ray, ultrasonic, or other 

appropriate tests to verify adhesion of 

the piston plasma coating are not 

necessary, and would increase the 

operators’ costs without an increased 

level of safety. Furthermore, we have 

determined, as previously mentioned, 

that we need to address degraded servo 

actuator performance due to internal 

leakage and piston head plasma spray 

flaking, which could potentially lead to 

loss of control of the helicopter. 

Therefore, we are revising the initial 

proposal to require only the leakage rate 

inspections and replacement of the 

servo actuators, Sikorsky P/N 76650– 

09805–109 and –110, with servo 

actuators, Sikorsky P/N 76650–09805– 

111, or replacement of servo actuator 

pistons, P/N 41004321, with P/N 

41012001 or P/N 41012001–001, in 

Sikorsky servo actuators, P/N 76650– 

09805–109 and –110. 

Copterline also states that 

inconclusive investigations into 

previous ‘‘unsolved accidents’’ 

involving Sikorsky Model S–70, S–76, 

and H–53 helicopters should be reexamined to determine if there is any 

relationship between those accidents 

and the more recent accident involving 

the Copterline helicopter that prompted 

issuing the NPRM. 

We do not agree that additional 

review of previous accidents involving 

Sikorsky helicopter models is necessary. 

Investigations of previous Model S–76 

helicopter accidents indicated no 

evidence of involvement of the servo 

actuators, therefore, we believe there is 

no relationship to the Copterline 

accident. Moreover, these servo 

actuators on those other Sikorsky model 

helicopters are significantly different in 

design, not susceptible to the same 

plasma flaking and seal leakage 

problems as the Model S–76 servo 

actuator, and would not provide useful 

information for evaluating the failure 

modes of the Model S–76 servo actuator. 

Copterline expressed concern that the 

servo actuator does not meet the part 29 

certification requirements to be a ‘‘failsafe component’’, and that it was not 

designed for the situation in which both 

return ports are blocked, which could 

cause the servo actuator to jam. As 

previously noted, they cite the NTSB 

laboratory findings as evidence that this 

dual blockage occurred, leading to the 

accident. Copterline states that the 

manufacturer of the servo actuator or 

the helicopter must demonstrate and 

prove that the servo actuator is a failsafe component and that the Model 

S–76 helicopter meets all the type 

certification requirements. 

We disagree with Copterline’s 

statement that the S–76 servo actuator 

does not meet part 29 certification 

requirements. The design of the affected 

Model S–76 helicopter servo actuator 

meets the fail-safe design regulatory 

requirements that were in effect at the 

time of initial certification of the Model 

S–76 helicopter. The inspection 

requirements of this revised proposal 

will assure that the Model S–76 servo 

actuator remains airworthy. 

Copterline states that ‘‘the FAA 

should require Sikorsky to make all 

Servo testing reports available without 

delay.’’ Copterline also states that 

‘‘servo testing results and findings for 

cases where both return flow ports are 

blocked should be released 

immediately, if they exist.’’ Also, 

Copterline states that the ‘‘specially 

manufactured and modified servo used 

in the Sikorsky testing’’ did not 

demonstrate conclusively what 

happened in the accident servo 

actuators. They further state that the 

Sikorsky testing does not establish that 

a servo actuator on the helicopter 

involved in the accident did not 

malfunction. 

We agree with the comment that all 

testing results and findings should be 

released and to our knowledge, all 

relevant and requested FAA agency 

records have been made available. With 

respect to the comment that Sikorsky 

did not demonstrate conclusively what 

happened in the accident, the parties 

involved in the accident investigation 

have conducted extensive investigations 

to determine the cause of the accident. 

Although the Estonian authorities have 

released a final report identifying a 

cause of the accident, these parties have 

not and may not ever agree on the cause 

of the accident. As previously 

mentioned, the FAA has determined, 

based on further information obtained 

from the Copterline accident 

investigation and other test and service 

history data since we issued the NPRM, 

that a need exists to address degraded 

servo actuator performance due to 

internal leakage and piston head plasma 

spray flaking. This is reflected in this 

proposal. 

Sikorsky states with respect to the 

accident, that the physical evidence 

does not support the theory that a 

mechanical malfunction of the servo 

caused the accident, and that it is 

physically impossible for the Model 

S–76 helicopter to perform these 

maneuvers without being influenced by 

an external force such as a waterspout. 

Copterline states Sikorsky’s comment is 

incorrect when it states that it is 

physically impossible for the Model 

S–76 helicopter to perform the 

maneuvers recorded on its own even if 

the servo actuator malfunctioned, and 

cites the accident helicopter’s flight data 

recorder (FDR) data as evidence that the 

accident helicopter stalled at 130 knots, 

and this stall is the external force that 

explains the maneuvers. They also state 

that if there had been any weather 

related cause to the accident, that it 

could have been read from the FDR 

data, and that there isn’t any data to 

support Sikorsky’s theory of a 

waterspout. 

The weather data and laboratory test 

data are inconclusive. We have 

determined that the Model S–76 servo 

actuator pistons may experience piston 

head seal leakage and plasma spray 

flaking, and are proposing the 1,500 and 

2,250 hours TIS leakage inspections and 

servo actuator replacement to address 

this unsafe condition. 

Finally, Sikorsky, in a second 

comment, states that the comments 

submitted by the NTSB in response to 

the previously issued NPRM are 

inaccurate or inconsistent with physical 

evidence or recorded test data. Sikorsky 

states that the Sikorsky testing fully 

demonstrated that all flight loads can be 

sustained in a triple ‘‘failure’’ condition, 

and that a ‘‘combined failure’’ with high 

leakage rates (3 times the in-service 

allowable leakage), 100 percent blockage 

of one of the two C3 ports, and loads 

associated with high airspeeds (and 

more significantly, the entire certified 

flight spectrum), will not overpower the 

servo actuator. They further state that 

they have briefed the NTSB and FAA on 

results of these tests and maintain that 

the testing demonstrates that the servo 

actuator design is safe and robust. 

As stated previously, the final report 

on the accident investigation has been 

released, and the parties involved in the 

investigation have not and may never 

agree on the cause of the accident. 

However, we have determined that there 


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Federal Register / Vol. 74, No. 27 / Wednesday, February 11, 2009 / Proposed Rules 6839 

is a need to require the servo actuator 

leakage rate inspections and replacing 

each affected servo actuator with a servo 

actuator containing a newly re-designed 

servo actuator piston to prevent 

degraded servo actuator performance as 

a result of piston head seal leakage and 

plasma spray flaking. 

Since this proposal changes the scope 

and the requirements of the originally 

proposed rule, we have determined that 

it is necessary to reopen the comment 

period to provide additional 

opportunity for public comment. 

We estimate that this proposed AD 

would affect 300 helicopters (900 servo 

actuators) of U.S. registry. We also 

estimate that the leakage rate inspection 

would take about 1 work hour per servo 

actuator at an average labor rate of $80 

per work hour, and the two leakage rate 

inspections on 900 servo actuators 

would cost about $144,000. We estimate 

that 6 servo actuators, Sikorsky P/N 

76650–09805–109 or -110, would need 

to be replaced with servo actuators, 

Sikorsky P/N 76650–09805–111. 

Assuming an estimated 8 work hours 

per servo actuator for installation and a 

cost of $57,000 per servo actuator, the 

total cost of installing these servo 

actuators would be $345,840. We 

estimate that the cost of replacing the 

pistons in the remaining 894 servo 

actuators would cost $7,259,280, 

assuming 14 work hours to replace the 

pistons and install the servo actuator, 

and a cost of $3,500 per piston (2 

pistons per servo). Therefore, the total 

estimated cost of this proposal is 

$7,749,120. 

Regulatory Findings 

We have determined that this 

proposed AD would not have federalism 

implications under Executive Order 

13132. Additionally, this proposed AD 

would not have a substantial direct 

effect on the States, on the relationship 

between the national Government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government. 

For the reasons discussed above, I 

certify that the proposed regulation: 

1. Is not a ‘‘significant regulatory 

action’’ under Executive Order 12866; 

2. Is not a ‘‘significant rule’’ under the 

DOT Regulatory Policies and Procedures 

(44 FR 11034, February 26, 1979); and 

3. Will not have a significant 

economic impact, positive or negative, 

on a substantial number of small entities 

under the criteria of the Regulatory 

Flexibility Act. 

We prepared a draft economic 

evaluation of the estimated costs to 

comply with this proposed AD. See the 

AD docket to examine the draft 

economic evaluation. 

Authority for This Rulemaking 

Title 49 of the United States Code 

specifies the FAA’s authority to issue 

rules on aviation safety. Subtitle I, 

Section 106, describes the authority of 

the FAA Administrator. Subtitle VII, 

Aviation Programs, describes in more 

detail the scope of the Agency’s 

authority. 

We are issuing this rulemaking under 

the authority described in Subtitle VII, 

Part A, Subpart III, Section 44701, 

‘‘General requirements.’’ Under that 

section, Congress charges the FAA with 

promoting safe flight of civil aircraft in 

air commerce by prescribing regulations 

for practices, methods, and procedures 

the Administrator finds necessary for 

safety in air commerce. This regulation 

is within the scope of that authority 

because it addresses an unsafe condition 

that is likely to exist or develop on 

products identified in this rulemaking 

action. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Safety. 

The Proposed Amendment 

Accordingly, pursuant to the 

authority delegated to me by the 

Administrator, the Federal Aviation 

Administration proposes to amend part 

39 of the Federal Aviation Regulations 

(14 CFR part 39) as follows: 

PART 39—AIRWORTHINESS 

DIRECTIVES 

1. The authority citation for part 39 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 [Amended] 

2. Section 39.13 is amended by 

adding a new airworthiness directive to 

read as follows: 

Sikorsky Aircraft Corporation: Docket No. 

FAA–2006–24587; Directorate Identifier 

2006–SW–05–AD. 

Applicability: Model S–76A, B, and C 

helicopters, with a main rotor servo actuator 

(servo actuator), Sikorsky part number (P/N) 

76650–09805–109 or –110 (also marked as 

HR Textron P/N 3006760–109 or –110), 

installed, certificated in any category. 

Compliance: Required as indicated, unless 

accomplished previously. 

To detect leaking in a servo actuator, 

which could lead to degraded servo actuator 

performance and subsequent loss of control 

of the helicopter, do the following: 

(a) For a servo actuator with 1,500 or less 

hours time-in-service (TIS) since new (TSN) 

or TIS since overhaul (TSO), determine the 

leakage rate on or before reaching 1,500 

hours TSN or TSO. 

(b) For a servo actuator with 2,250 or less 

hours TSN or TSO, but more than 1,500 

hours TSN or TSO, determine the leakage 

rate on or before reaching 2,250 hours TSN 

or TSO. 

(c) If the leakage rate in any servo actuator 

exceeds 700 cc per minute when performing 

the leakage rate inspection specified in 

paragraph (a) or (b) of this AD, then: 

(1) Replace that servo actuator piston, HR 

Textron P/N 41004321, with a servo actuator 

piston, P/N 41012001 or P/N 41012001–001, 

and re-identify the servo actuator on the 

servo actuator data plate as Sikorsky P/N 

‘‘76650–09805–111’’ and HR Textron P/N 

‘‘3006760–111’’ using a metal stamp method; 

or 

(2) Replace the servo actuator with an 

airworthy servo actuator, Sikorsky P/N 

76650–09805–111, HR Textron P/N 3006760– 

111. 

(d) On or before 3,000 hours TSN or TSO, 

whichever occurs first, replace each servo 

actuator piston and re-identify the servo 

actuator as specified in paragraph (c)(1) of 

this AD or replace each servo actuator as 

specified in paragraph (c)(2) of this AD. 

(e) Modifying and re-identifying each servo 

actuator as specified in paragraph (c)(1) of 

this AD or replacing each servo actuator as 

specified in paragraph (c)(2) of this AD is 

terminating action for the requirements of 

this AD for the modified and re-identified or 

replaced servo actuator. 

(f) To request a different method of 

compliance or a different compliance time 

for this AD, follow the procedures in 14 CFR 

39.19. Contact the Manager, Boston Aircraft 

Certification Office, FAA, ATTN: Terry Fahr, 

Aviation Safety Engineer, 12 New England 

Executive Park, Burlington, MA 01803, 

telephone (781) 238–7155, fax (781) 238– 

7170, for information about previously 

approved alternative methods of compliance. 

Issued in Fort Worth, Texas, on January 16, 

2009. 

Mark R. Schilling, 

Acting Manager, Rotorcraft Directorate, 

Aircraft Certification Service. 

[FR Doc. E9–1688 Filed 2–10–09; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF HOUSING AND 

URBAN DEVELOPMENT 

24 CFR Parts 5, 92, and 908 

[Docket No. FR–4998–N–03] 

RIN 2501–AD16 

Refinement of Income and Rent 

Determination Requirements in Public 

and Assisted Housing Programs: 

Proposed Delay of Effective Date 

AGENCY: Office of the Secretary, HUD. 

ACTION: Notice of proposed delay of 

effective date. 

SUMMARY: In accordance with the 

memorandum of January 20, 2009, from 

the assistant to the President and Chief 


dwashington3 on PROD1PC60 with PROPOSALS