### Docket No: 

### FAA-2012-1093 Directorate 

### ID: 2011-SW-020-AD Originating Office Tracking No.: 

### Disposition Comments

Next 

### Step: 

## iZ1 FRAN 

## 0 SNPRM 

## D These comments are in response to an 

### SN PRM



## D No Comments/Only Supportive Comments Received

- ljthis box is checked , no signatur es are required Yes 

### 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 the previously published NP RMwill require a new notice. Contact the Directorate focal point for guidance. 

### See the next pages 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 from 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-8040.1 C Chapter 9. ISSUE 1: 

### Select one of thefollowing: 

## If

other, explain: Commenter(s ): What change to the AD action is requested? Why is the change requested or how is itjustified? Do we agree? If YES, we agree because Make the following changes to the AD: JfPARTIALLY AGREE, we agree with because We disagree with because Make the following changes to the AD: If 

### NO, we don't agree because

ISSUE 

### 2: Select one of the following: 

## If

other, explain: Commenter(s): What change to the AD action is requested? Why is the change requested or how is itjustified? Do we agree? If YES , we agree because Make the following changes to the AD: lfPARTIALLY AGREE , we agree with because We disagree with because Make the following change s to the AD: 

### Page 1 of3

### If NO, we don't agree because

For additional issues, double-click here



### Page 2 of3

### Signature Section Signature indicates concurrence with this action. Originating Office Tracking No.:

# ~ ASE Printed Name: 

### Marc Belhumeur 

### { ate

Branch Manager



### Page 3 of3Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

I. Issue: Other (Kevlar Clutch) 2. Issue: Other (Education and training) 3. Issue: Other (A llowing some amount of cracks) 4. Issue: Other (Allowing some delamination) 5. Issue: ApplicabilitY (Remove 248-10 I and 248-202 blades from the AD) 6. Issue: Other (I

dentify unapproved blade spars and hinge blocks) 7. Issue: Withdraw the NPRM (Questions asked) 8. Issue: Oelav Issuance of AD () 9. Issue: Other (Modify the NPRM) 10. Issue: Other (Allowing dent , nick, crease, wrinkle, bend) II. Issue: Other (Certified repair center and repair process specitication) 12. Issue: Other (Lessen inspection requirements) 13. Issue: Withdraw the NPRM (Eliminate AD

- Follow Maintenance Manual) 14. Is s ue: Service Info (Rewrite/eliminate the Service Bullet in SB-111) 15. Issue: :Service Info (Proposed SAIB)Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

1. Issue: Other (Kevla r clutch) Commenters: Jerry L. Toms What they want changed: This commenter saw the need to equip these aircraft with Kevlar clutch lining. How they justify it: The Kevlar clutch dramatically reduces some ofthese blade overloads that cause the wrinkles , cracks etc. They do not create clutch dust in the main centrifugal drive and offer an incredible difference in rapid engagements without sticking or other known operational issues

. And it was inexpensive. FAA Response: We disagree. We have no basis to require the manufacturer to obtain FAA approval for a design that it has not proposed , particularly when we have been provided with no supporting data to justify that it will address the unsafe cond ition. 2. Issue: Other (Education and training) Commenters: Jerry L. Toms What they want changed: Thi s commenter recommended a training program for maintenance providers, operators, and owners with respect to the blades, regarding several subjects including: the sign ificance of the placards, TCDS instructions, operating limitations and the FA A Approved Rotorcraft Flight. How they justify it: He saw the real issue to be educational and proper maintenance and operation of the aircraft and its components. One ofhis goals is to have those responsible for maintaining these machines and all other GA aircraft

.to see the drastic need these days for seeking additional training and taking it serious l y so that GA can remain fun and safe. He believed the need is for education about the machine , the engineering and safety which already exists , and the greater need for transferring the knowledge that existed in the high utilization and activity years of development ofthe Brantly helicopter ; to those involved with it today as operators , maintenance providers , and regulators charged with safety ofthe fleet. FAA Response: We disagree. Individuals responsible for maintaining and operating an airworthy helicopter are required to know the significance ofplacards , TCDS instructions , and operating l imitations. More training could be beneficial , but we have rece ived no in fonnation that it would address the unsafe condition. 3. Iss ue : Other (Allowing some amount of cracks) Commenters : Ronald S pik er, Jerry L. Toms What they want changed: Crack should be allowed per the approved factory maintenance inspection procedures. How they justify it : Method of inspections and criteria for permissible crack size and location are availab le in the Maintenance Manual and Service Letters. One ofthe commenters noted he was veryBrantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

involved in the manufacturing ofthese blades and the implementation of approved repair process specifications and clarification of limits of acceptable cracks in the skin, hinge block, and spar attachment hole. Those limits are published in historical TC Holder documents including service documents. FAA Response: We disagree. Allowing any cracks in a blade would be unacceptable. No data suppotts that a crack in these blades is a safe condition. 4. Issue: Other (Allowing some delamination) Commenters: Ronald Spiker, Alan Bowles , Jerry L. Toms What they want changed: Delamination should be allowed per the service bulletin. How they justify it: The service bulletin allows for up to I0 sq.in of delamination outside ofthe inboard 12 in. of the main rotor blade; which they stated is closer to industry standard for other helicopter manufacturer' s maintenance procedures and is allowed per Brantly maintenance manuals. There is also acceptable delamination limits published when the Brantly B2 was highly used. FAA Response: We partially agree. We agree that not allowing any delamination outside ofthe inboard 12 inches doesn't align to industry standards. We disagree with allowing up to I0 square inches of delamination per the service bulletin because I0 square inch es is too large to align with industry standards and also because there is no supporting data that justifies that a larger delamination area in these blades would address the unsafe

. condition. We will allow for up to 2 square inches of delamination outside ofthe inboard 12 inches. We wi ll define the unsafe condition for the outboard ofthe inboard 12 inches as 2 or more square inches of delamination. 5. Issue: Applicabilitv (Remove 248-10 I and 248-202 blades from the AD) Commcnters: Gerald E. Goldsberry, Jerry L. Toms What they want changed: One commenter requested that the 248-10 I and 248-202 blades be removed from the AD. The other asked to address 248-10 I and 248-202 blades separately from 248-404 blades. How they justify it: The 248-10 I and 248-202 have been good blades for over 50 years; the only reason the get cracks is because of improper maintenance , rigging, and operation. The 248-1 0 I and 248-202 blades have FAA approved process specifications for authorized repair station to overhaul and repair those blades. The 248-202 blades and the 248-404 blades are significantly different in composition and bonding agent. The 248-404 was more susceptible to bonding separation ; from 200 I to 2006 , the DER experimented on the 248-404 trying to find the proper replacement foam and bonding agent. There are limited 248

-202 used blades that are airworthy and no factory support on any parts. Issuing the AD as is will put all Brantly owners out ofbusiness. FAA Response: We disagree because failures and fractures have occurred in the PIN 248-202 blades. Thes e failures have occun-ed in the field and show that the previous spec ifications the commenters referenced are inadequate. We have been provided with no supporting data that shows a crack occurred because of improper rigging , maintenance , or operation ofthe aircraft. These issues are already addressed in Brantly ' s maintenance manuals , flight manual supplements (FMS), service bulletins , and service instructions. Brantly, with help from a laboratory report written by a metallurgical engineering company ,Brant ly M/R Bl ade AD, Docket No. F AA-2012-1093, Disposit i on of comments:

concluded that the M/ R blades' failure was caused by hydrocarbons contamination in side the blades ' skin

to-foam bond and that the fractures originated near the trailing edge. The P /N 248-10 I and PIN 248-404 are s imilar in construction to the P IN 248 -202 blades , and thus need to be included and addressed in the AD. We have been provided with no data that shows that the PIN 248-404 is more susceptible to bonding separation. The PIN 248-10 I and 248-202 blades have been addressed separately from PIN248-404 blades in that the AD does not require the P IN 248-404 blades to do many of the inspections until after 10 years or 1 ,000 hours TIS, instead of within 8 hours TIS like the other blades. We do not issue an AD based on whether spare parts are available or can be produced. While every effort is made to avoid grounding aircraft, we must address the unsafe condition. 6. Iss u e: Ot her (Ident ify unapproved b lade spars and hinge b locks) Comm e nte r s: Jerry L. Toms Wh at th ey wa nt c h a n ged: This commenter recommended a mandatory in spection to identifY unapproved blade s pars and hinge blocks using a developed ma in rotor blade rivet ho l e template for comparison. Ho w t h ey jus tif y it: This will help identifY unapproved blade spars and hinge blocks. There is a need to att

empt to identifY main rotor blades which were not produced or repaired using an FAA approved quality system or materials or processes: Where rivet hole edge distance or pattern has been cited in your NPRM documentation; any improper edge distance identified by the template shoul d be addressed appropriately. FAA Res p o n se: We disagree because the lab report concluded that the M / R blade failure was caused by hydrocarbons contamination inside the blades' skin-to-foam bond and that the fracture originated near the trailing edge. Obviously , parts produced or repaired using an FAA-approved quality system, materials or processes is important and eliminating short rivet hole edge distances is good design practice. But no data suppor ts that the spar or hinge block was unapproved or that the rivet hole edge distance or pattern caused the unsafe condition. 7. Iss u e: W ithdraw the N PRM (Q uest ions asked) Co mm e n te r s: Jerry L. Toms Wh at th ey wa n t c h a n ged: To withdraw the AD until more analysis /testing is performed. H ow th ey j ustify it: It is prudent to understand these additional stress sourc es and moments before making conclusions about the root cause factors of cracks in the stated skin locations; and certain ly before asserting these are related to "age" and "f atigue' '. Prior to issuing an Airworthiness Directive, the root cause should be identified with spec ificity, with the particular manufacturing method and material s identified to ensure that the corrective action is appropriate. Questions: I. What testing was performed to determine that the spars and hinge blocks. based on "age", no longer meet the minimum design specifications under which they were se lected and approved as the structural blade components for the 82 Series?Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

2. Can you supply me with the name of a lab wh o could perform des tructive testing on a blade or two and provide me with a report concerning whether it actually no longer meets the minimum de s ign specification as related to the airworth iness requirements and strength? 

### 3. Did you perform this analysis in conjunction wi th this NPRM? 4

. How many blade fai l ures ofthe spar and hinge block assembly were documented in preparation of this NPRM Proposal for an Ai rworthiness Directive? 5. What is the structural s i gnificance ofthe rivet hole statements related to the l eading edge spar and the root hinge block where the skin attaches? What is the function ofthese rivet holes and rivets? 6. In this propos al, there is mention of one event in New Zeal an

d, referenced as an "acc ident"; and half a dozen other blades with either skin cracks or del am inat ion defects

. What percentage of the estimated four thousand (4000) 248-10 I and 248-202 blades manufactured or repaired us ing FAA approved methods , does t hi s represent? 7. What serial number sequences were invol ved? Which bonding materials ? Which foam core materia l? Which type ofrivets was involved? Which model blades? 8. Your Cost assessment fails to address the FAA approved dra

.. vings whi ch state that a 248 -404 b l

ade cannot be used in place of a -202 blade: A r e they s ti ll required to be replaced in sets of three? FAA Res ponse : We disagree. The AD was issued because it addressed an unsafe condition. The root cause ofthe fai lures has been demonstrated by Brantl y with help from a laboratory report written by a metallu rg ica l engineering company . The report took into account stresses and loading, and determined that skin fracture was propagated by corros ion-fatigue and mechanical fatigue. That report concl uded that the M

/ R bl ades failure was caused by hydrocarbons contam ination ins ide the blades ' skin-to-foam bond an d that the fracture originated near the tra i ling edge

. Answers to questions above: ( I) The original blades were certified using a crack initiation methodology (e

. g., using the S-N curves and Miner's Rule). Shortl y after certification, a fat igue test was accomp li shed on the mid-span ofthe spar and skin. No supporting data or test results were provided to determine if the spars and hinge blocks no longer meet the design specification s. Stereomicroscopy, wavelength dispersive X-ray spectroscopy , combustion testing, tensile testing, peel testing, scanning electron m icroscopy, micro Fou rier infrared s pectroscopy, and hardness testing were all performed and documented to determ ine the causes ofthe delamination and crack propagation. No testing is needed to detennine whether blades with delamination and cracks do not meet the design

. (2) The name ofthe company that performed the Failure Analysis is Metallurgical Engi neering Servic es. We are not distribut ing the lab report. A copy must be requested from Brantly. No lab report is needed to determine that blades with delamination and cracks are not a irworthy or have reduced strength. (3) A M /R Blade Failure Analysis, Risk Analysis, Cost Analysis, and Economic Analysis were performed before the NPRM was issued

. (4) None. Th e failures were found in the skin to foam bond and in the skin and rivets at the rivet joints attaching the skin to the hinge block and /or spar.Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposit ion of comments: (5) The cracks originated near the skins' trailing edge and propagated bet'vveen rivet holes and into the leading edge rivet holes. These rivets carry shear between the hinge block and skin and the spar and skin

. (6) The percentage has not been determined or needed for this AD

. (7) No serial number sequence has been determined or was needed s ince the part numbers are only needed to identify the applicab l e blades. Per the laboratory report, the bonding material between the skin to foam was 3M 1239 & 3M 11239A , the foam core was Stafoam AA604, the type ofrivets were AAIIOO, and the blade was PIN 248-202. (8) All three blades installed on one helicopter must have matching part numbers. T he cost analysis already assumes that the replac ement blade must match what it is replacing, thus no new cost analysis is needed. It doesn ' t assume that three blades must be replaced because the AD doesn 't require it. 8. Issue : Delay Issuance of AD Commenters: AOPA, Jerry L. Toms What they want changed: Extend comment period. How they justify it: So the owners/operators can do some research on the AD and on the costs of rep lacem ent blades, a thorough review ofthe NPRM, and provide adequate comments. Because the conclusions drawn by the FAA from the limited findings; are inconsistent with the historical research by the original TC Holder, the PC holder, and the Certified Repair Stations which were affiliated with the TC Holder in the 1960 's and 1970 's into the 1980's, when there were high utilization operators in Illinois , Pennsylvania, Florida and other states. Al so the causal factors are well defined , and not related to fatigue or failures in the FAA Approved manufacturing and repair process specifications. FAA Response: We disagree because the FAA has included and accepted all comments received after the comment period ended. We notified AOPA and the other commenter prior to the comment period ending that we would include all comments received until February 15 , 2013. The FAA also had adequate informat ion to make its detenninations. T he root cause of the failures has been demonstrated by Brantly , with help trom a laboratory report written by a metallurgical engineering company. That report concluded that the M/R blades failure was caused by hydrocarbons contamination inside the blades ' skin-to

-foam bond and that the fracture originated near the trai li ng edge. No supporting data has been provided that shows that the AD is inconsistent with history or that the root cause is not related. The is suance of an AD cannot be determined on the cost ofreplacement blades. While every effort is made to avoid grounding of aircraft, we are required to address the unsafe cond iti ons. 9. Issue: Other (Modify the NPRM) Com menters: Neil Freeman What they want changed: The commenter requested that the proposed AD be modified. He proposed that all used blades installed initially be checked. How they justify it: The commenter attributed the cause ofthe blade condition to the incorrect installation ofthe blade damper units as he experienced it. The check would be fairer to owners who currentl y can ' t buy new blades. He stated the New Zealand Brantly that initiated the AD appeared to be maintained on a farm.Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

FAA Response: We disagree because no data shows that the damper caused the unsafe condition. An initial check for improper damper installation is not merited. There is history that the incident helicopter may have had quick starts, and that the dampers had to be replaced, but the quick starts and damper issues have not been substantiated to be the root cause. Proper damper installation is paramount, but there are already adequate damper inspections and installation instructions in the maintenance manual and service instructions. 10. Issue: Other (Allow ing dent, nick, crease , wrinkle , bend) Commenters: Gary Goldsberry, Ronald Spiker, Alan Bowles, Cy A. Russum, Jerry L. Toms What they want changed: Overall, the commenters requested that small dent, nick, crease, wrink le, or bend be allowed in the blades per the approved factory maintenance inspection procedures. One of these commenters did state that blades with wrinkled skins should be replaced. How they justify it: A small dent, nick, crease, wrinkle, or bend in the skin of the blade, especially in the middle or trailing edge, does not cause the blade to crack and is not necessarily a safety is sue. All Brantly blades are tabbed on the last 18" of the blade to get cyclic pressures correct or to cure a climbing or diving blade. During certification and flight there are procedures which require the outboard end of the trailing edge of the blade to be bent. Wrinkles , bends, and nicks should be allowed as previously li sted in the approved factory maintenance inspection procedures. One of the commenters noted he was very involved in the manufacturing of these blades and the implementation of approved rep air process specifications and clarification of limits of acceptable blade skin \-vrinkles, bends , and other approved conditions. Those lim its are published in historical TC Holder documents including service documents. Most Brantlys will end up being grounded due to sl ight imperfections in the main rotor blades that are not a safety issue. Even one blade with a small dent in the skin, a nick, or even a bend from being tabbed would ground the helicopter due to pulling the blade from serv ice. FAA Response: We agree. The data we have does not support that a crack in the Brantly rotor blade skin s was caused by small dents, nicks, creases, wrinkles, bends, extra hole, and inadequate rivet spacing , though eliminating them is good design practice. We will remove the dent, nick, crease , wrinkle , bends , extra hole, inadequate rivet spacing requirements. 11. Issue: Other (Certified r epa ir center and repair process specification) Commenters: Bryan Cobb , Jerry L. Toms What they want changed: One of the commenters asked for the possibility to license a certified repair center to rebuild the blades, if the crack and the spar and hinge-block have not reached their life limit. The other asked to locate and update the approved process specifications which existed at the FAA Approved Repair Station , and estab li sh a method to revive the repair process specifications including the approved blade re-skinning, using currently available materials and processes. The commenters requested that thereskinning of the blades be allowed in the field. How they justify it: The repaired blades could provide more hours of safe flying until the life of the spar and hinge

-block is exhausted. There is currently no approved facility approved to rebuild outer blades with cracked skin. The supply of used, serviceable blades is minimal at best. Owners will not be able to replaceBrantly M/R Blade AD, Docket No. FAA-2012 - 1093, Disposition of comments:

thes e blades

. Thes e blades are not complex as many other. These helicopters have operated with this i s sue for decades without a single accident attributed to failed rotor blades

. Blades that are suspect e d to be reskinned in the field do not fall into the categor y of unsafe blades. One comment e r s aid he participated in the Brantly ' s blade repair processes in the mid 1970's ; these processes performed in repair station involved re-skinning of the 248-202 blades using the approved methods. The update of these specifications will e nabl e FAA approved blade repairs and updates; coupled with detail e valuations of each blade rec e ive d for rebuilding , to enhance the database of issues. Within the last two years , the Brantly Company has moved to China and the supply ofN EW outer rotor blades instantly went to ZERO! If this A.D. is adopted with its current wording, it will effectually ground all flying Brantlys until some source for new blades i s found or some facility is certified to re-build the blades. FAA Response: We disagree. The FAA does not license repair centers, we certificate them. We do not have the approved process specifications or data to locate or to revise/update/ support returning /rebuilding/re-skinning blades to an airworthy condition. Repairs that eliminate the cracks (stop drilling is not allowed) and delamination can be accomplished by appropriately rated skilled mechanics and repair stations. The repairs must be done with adequate tooling, perF AA approved repair data , and approved for return to service as a major repair. FAA cannot base an AD on whether spare parts are available or can be produced. While every effort is made to avoid grounding aircraft, we must address the unsafe condition 12. Issue: Other (Lessen inspection requirements) Commenters: Bryan Cobb , Gerald E. Golsberry, Ronald Spiker, Alan Bowles , Gregory Thomas What they want changed: Several commenters requested that the eddy current inspection be eliminated from the AD. One of the individuals asked to consider performing a verification and validation of the eddy current inspection prior to issuing the AD. Some requested a I OX magnification glas s inspection for cracks and delamination each 50 or I00 hour inspection, similar to the Robinson AD 2011-12-10. One commenter recommended visual inspection for cracks utilizing a 3 to 

### 5 magnification magnifying glas s ; with possible chemical stripping prior to the inspection. One commenter asked that the blades inspection be perform by an authorized A&P annually ; another that the blades be inspected at their locations. There was also a request that the visual inspection prior to the first flight of each day be performed by the helicopter owner or operator. How they justify it: The eddy current testing can ' t be done successfully at c ertain locations on the Brantly helicopter blade , especially between the leading edge of the skin to the main spar, due to the closeness of the rivets in the blade spar at the edge. It can cause erroneous indication s that would lead to inaccurate res ults ; b ecause the defects that wil l be found the eddy current test do not constitute an unsafe

. condition. Due to the very thin material thickness , cracks should be through the material should be visible utilizing a magnifying glass between 3 to 5 magnification. Larger magn ifying optics could be used , but they beg in to be very hard to focus and the images become distorted. The area between the rivet and the skin edge should be stripped as necessary to allow b ette r vi s ibility. Che mical stripping would be best to kee p the metal from be ing " sme ared" which could happen by mechanical stripping. These helicopters have op e rated with thi s iss ue for d e cades without a s in g le accident attribute d to fail ed ro t or blades . One comme nte r s tate d it was suggested that it would destroy the blade itself. Another commenter listed differe nt costs associated with getting blades through an eddy current inspection as well as possibility of damage and down time. The Brantl y Co mpany has moved to C hina and the s upply of N EW oute r ro tor blades in stantl y went to ZERO! There is currently no approved facility approved to rebuild outer blades with cracked skin. T he s uppl y of used , serviceable blades is minimal at best. Owners will not be able to replac e these blad es . l fBrantly M/R Blade AD, Docket No

. FAA-2012-1093, Disposition of comments:

this A.D. is adopted with its current word ing, it will effectually ground all flying Brantlys until some source fo r new blades is found or some facility is certified to re-build the b lades. FAA Re s ponse: We partially agree. Reducing the eddy current inspection area to just the tirst inboard 12 inches is adequate because thi s is where th e fracture is located

. Eddy current inspecting the outboard area would not be effective in find ing the unsafe condition. We disagree with eliminating the eddy current inspection procedure altogether because the inspection shou ld find the unsafe cond ition, is reasonable , widely used, is cost effective, and has been addressed in the AD impact ana l ysis

. No alternate procedure has been provided that can address the unsafe condition as reliably

. The eddy cuJTent in spection procedure has been validated and is similar to other blade crack inspections. The procedure takes edge effect into account. There may be some false indication , but these shou ld be false positives , which can be reevaluated

. The procedure is a nondestructive inspection (ND I) and if done correctly , will not destroy any blade

. The procedure can be done in the field if the inspection area is clean , has proper lighting , there is the proper equipment, and can be done by a qualified inspector. The procedure is needed to find small cracks around the r ivet holes that can quickly link up , called multiple s ite damage (MSD ), and cause rapid failure . The procedure is too specialized to allow any A&P to do unl ess he or sh e is a qua l ified to L eve l II or equ ival ent. Visual and/or magnifying glass inspections are not as effective as eddy current and are already being done every 25 hours with a IOx magnifying g las s. The 3x or 5x is magnifying glass may miss crack s . Th e 25 hours matches the regular Brantly maintenance inspection schedul e, and no data has been provided th at supports that incre asing the interval to 50 or I00 hours wou ld address the unsafe condition. We agree with the visual in spection before the first flight o f each day being performed by th e helicopter owner or operator since this is best accomplished as part ofthe other daily in spections and does not require tools. The issuance of an AD cannot be determined on whether spare parts are available or can be produced. While every effort is made to avo i d grounding of aircraft, we must address the unsafe condition. Make the following changes: Reduce the eddy current inspection area to just the first inboard 12 inches. Define that a crack in the first 1 2 inches is the unsafe condition. Allow helicopter owners and operators to perfonn the vis ua l inspection before the first flight of each day. 13. Issue: Withdraw th e NPRM (Eliminate AD- Follow Maintenance Manual) Commenters: Cy A Russum , Anonymous , Allen Bowles, Jer ry L. Toms, Neil Fr eeman , B ill Mott What they want changed: These commenters requested withdrawal ofthe AD with the proposal to use the original Maintenance Manual ' s blade inspection and Serv i ce L etter(s) in stead

. How they justify it: The commenters attribu ted the cause of the cracking ofthe blade s to improper rigging, maintenance or operation of the aircraft. The Brantly has some unique designs to include that the rotor brake must be on for starting. Ifthi s procedure is not followed there will be excess ive torque applied on the attachment point ofthe main rotor blade. Damage depends on the severity ofthe quick start and may include damage to the skin or breaking the bond

. Commenters believes that the reason s a 248-10 I or 248

- 202 b lade gets cracks is the lack of maintenance , bad inboard bearings, bad dampers or rotor system out of phase. The maintenance manual has adequate inspection methods when followed properly

. Many defects cited as unsafe conditions in the NPRM are allowed per the original maintenance and overhaul manuals. The NPRM has not demonstrated there is any unsafe condition involving the structural blade el ements manufactured or produced or repaired in the FAA approved quality system or in the approved repair process specifications. During initial testing , for military use , the helicopter was demonstrated to have the ability to be flown and land safel y with portions ofthe blade removed. There has not been an accident related to blade fai l ure in over forty years. There has been only one accident attributed to blade failure inBrantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

the entire history of Brantly. The incident in New Zealand promoted the proposed AD. The aircraft was able to land safely even with a huge piece ofthe blade missing

. Few used blades would meet the onerous working in the Service Bulletin / AD effectively grounding the entire fleet of Brantlys. Additionally the company that wrote the Service Bulletin referenced in the AD did not have the authority to make parts for the rotor blades or produce this aircraft. Few used blades would meet the requirement ofthe AD. It would be financially devastating to the majority ofowners and lead to grounding the fleet. FAA's Response: We disagree because the failures that have occurred in the field show that the blades have an unsafe condition and that the original maintenance manual and service letters do not have adequate inspection methods to address them. We have not been provided with any supporting data that justifies eliminating the AD or that shows that cracking is caused by improper rigging, maintenance, quick starts , bad dampers, bad bearings , phasing, operation of the aircraft, or because they were not produced or repaired in the FAA approved quality system or with an approved repair process specifications. The incident helicopter may have had quick starts and dampers that needed to be replaced , but that has n ever been substantiated to be the root cause . Also, since improper rigging , quick starts, bad dampers, bad bearings , phasing, maintenance , and or operation ofthe aircraft are already addressed in Brantly 's maintenance manuals , Flight Manual Supplement (FMS) , service instruction , and service letters, they should not cause cracking if the aircraft is operated and maintained properly. Whether they contribute to cracking or not, they should be found by the normal maintenance inspections. Brantly, with help from a laboratory report written by a metallurgica l engineering company, concluded that the M /R blades failure was caused by hydrocarbons contaminati on inside the blades skin

-to-foam bond and that the fracture originated near the trailing edge. We do not issue an AD based on whether spare parts are available or can be produced. While every effort is made to avoid grounding of aircraft, we must address the unsafe conditi on . 14. Iss ue: Service Info (Rewrite/eliminate the Service Bulletin SB- I II) Commenters: Bill Mott, All en Bowles, Gregory Thomas What they want changed: The commenters requested a rewrite ofthe Service Bulletin SB-111 and one of them provided the suggested content. Another commenter asked that the Service Bulletin SB-11 I be rescinded and requested that the original Maintenance Manual 's blade inspection and Service manuals be followed

. Brantly Service Bulletin No: Ill -Suggested Rewrite or Replacement Introduction No changes necessary. App licability No changes necessary. Compliance For Outboard Main Rotor Blades PIN 248- I0 I , 248-202, and 248-404, before further flight , comply with sections I and 2 ofthis service bulletin

. Thereafter at intervals not to exceed I00 flight hours or 5 calendar years , whichever occurs first, comply with section I , and at intervals not to exceed 25 flight hours comply with section 2. Also comply with section 3 ofthis service bulletin before the first flight of each day. Contact No changes necessary. I Crack Inspection ( I00 Hour Inspection)Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments:

1.1 R emove the outboard main rotor blade. Clean surface to be inspected. Remove any contaminates that might interfere with the discovery of existing s urf ace indications. Use a suitable light and a lOX magnifying glass to inspect for cracks in the main rotor blade. Pay particular attention to areas around rivet holes , the blade root area, and the trailing edge. 1. 2 No cracks are permitted. Verify adequate edge distance between holes s uch that no additional holes have been added or extra rivets used to fill stop drilled holes in the root fitting. Any blade that has cracks (especially around the root ofthe blade), extra rivets , or stop drilled holes must be removed fi·om service. If any ofthese defects are found, remove the blade fTom service and replace with an airworthy part. Record the results in section 4 ofthis service bulletin. 1.3 Perform the 25 hour delamination inspection as described below

. 2 Delamination Inspections (25 Hour Inspection) 2.1 Clean surface ofthe outboard main rotor blade to be inspected. Remove any contaminates that might interfere with the discovery of existing surface indications. Use a suitable light to inspect for cracks in the main rotor blade. Pay particular attention to areas around rivet holes, the blade root area, and the trailing edge. 2.2 No cracks are permitted. Verify adequate edge distance between holes such that no additional holes have been added or extra rivets used to fill stop drilled holes in the root fitting. Any blade that has cracks (especially around the root ofthe blade), extra rivets, or stop drilled holes must be removed from service. If any ofthese defects are found , remove the blade from service and replace with an airworthy part. Record the results in section 4 ofthi s service bulletin. 2.3 Inspect the blade for delamination using a tap test. Use a metallic coin or tap hammer to lightly tap the blade in the areas that are bonded. Pay particular attention to the inboard 12 inches ( .305m) on the top and bottom. Mark all delaminated areas with a grease pencil or chalk. NOTE D elaminated areas will have a duller, low pitched sound when compared to areas that are not delaminated. They may also have a spongy or loose feeling when pressed with the hand

. 2.4 No delamination is permitted on the inboard 1 2 inches ( .305m). Delamination is permitted outboard of this area provided the total delaminated areas do not exceed I0 in2 (.254m2). Record the resu lts in section 4 ofthis service bulletin. 3 Daily Inspections 3.1 Before the first flight of each day, visually in spect the outboard main rotor blade for cracks. Pay particular attention to the blade root area and the area around the lead / lag damper mounting fork. 3.2 No cracks are permitted. If any are found , remove the blade from service and replace with an airworthy part. Record the results in section 4 ofthis service bulletin. 4 Inspection Report for SB- I II No changes necessary How they justify it: There has only been one accident related to the main rotor blades; more than 40 years ago. The Brantly in New Zealand landed safely, even with a huge piece ofthe blade missing

. Improper maintenance and operation are the causes of the problems found with the blades. The Brantly factory service manual and operating manual address these issues and allow continued safe flight. The eddy current inspection in SB -111 is not appropriate. Some ofthe individual who participated in the proposed rewriteBrantly M/R Blade AD, Docket No. FAA-2012-1093, Disposi t ion of comments:

included people who worked on the development ofthat helicopter, fl i ght schoo l operators and m echanic s . Issuing the AD as is will be devastat ing to Brantly 's stakeholders (flight schools, instructors , entities sell ing parts, ma intenance facilities, owners,). Small deformation in the skin shou ld be excepted unless they are in th

e area ofth e rivets. Wrinkl es and bend s a re common in these blades due to tabbing that was performed at the factory during the initial tracking and should still be allo wed

. In add ition de lamination in certa in areas should be allowed. The serv ice bulletin allows for up to I0 square inches of delamination outside of the inboard 12 inches ofthe M / R b lade. Similar criteria are used for other OEMs. FAA Response. We partially agree. Because the Brantly in New Zealand landed without f urther damage , it was invo lved in an incident ins t ead of an accident. The Final Rule will reflect this change. W e agr ee with a llowing some imperfections (See Issue: Allow Some Imperfections). We d isagree with rewriting the service bulletin because the FAA did not produce it. We a lso disagree that improper maintenance and operation caused the blades ' problems and that the Brantly fac t ory service manual and operating manual address these issues and allow continued safe flight (See Issue : Replace the AD)

. We also disagree with chang ing the in spections cited in the propos ed service bulletin because the proposal eliminates a necessary eddy current inspection and allo ws to o much duration between the magnifying g lass in spection s (See Issue: Reduce Inspection Requirements) and pennits delamination up to 10 square- inches (See Issue: Allow some delamination). Also , ADs are not issued based on the cost ofrem edy ing the safety issue. While every effort is made to avoid grounding of aircraft, we address the un safe condition. 

### t 5. Iss ue: Service info (Proposed SAJB) Commenters: Jerry Toms What they want changed: This commenter proposed an SAIB and provided its content as follows: I. On a one time basis for those helicopters where such an in spection has not been documented; rem ove the outboard blades and inspect the outboard main rotor hinge for binding. chaffi ng at the outboard !lapping hinge bearings and condition ofthe attachment hardware. 2. In spect the main rotor lag damper for delamination, chaffing ofthe m etal plates with the damper cage, and polish any grooves in the in side diame ter of the damper cage smooth to stop inadverte nt los s of damping action; and reassemble the damper and cage assembly. 3. In spect the damper attachment l ugs (threaded portion) to ensure it is not hitting the trailing edge blade cross section and if so. grind the end slightly to ensure clearance when properly adjusted in accordance with the manufacturers rigging instructions. 4. Weigh each main rotor blade (outboard) and compare static weights. If any blade is more than 2 ounces different, contact a service facility which can match balance the blades using the approved method. 5. Once blades are m atc h balanced, rein s tall them and rig them in accordance with the manufacturer's maintenance manua l. 6

. Dynamically balance the main rotor system using an ACES or Chadwick or simil ar system until the vibration is below .08 ips (it is possible with properly matched and rigged blade sys tem s to achieve levels as low as 0.0 I ips from a hover to Vne). Repetitive In spections: I. On a daily basis , perform a tap test in accordance wi th the original Brantly Maintenanc e Publications. checking for any ev idence of de l amination or the sk in to the foam core. 2. At the Annua l Inspection for low utilization persona l aircraft and at each 100 hour inspection for aircraft used in flight training or commercial operations of higher utili z ation. vi s uall y check the rivet areas at the leading edge s par and hinge block for defonnation and cracking. follo win g the limits published in th e original Brantly maintenance pub lications .Brantly M/R Blade AD, Docket No. FAA-2012-1093, Disp ositio n of comments:

Special Inspections : After any overload event such as a "Quick Start" or "hard landing" or failure to bottom the collective below 250 rotor rpm. perform the follow ing special in s pections : I. In spect main rotor centrifugal clutch area for dust and clean out with compr essed air 2

. Check attachment of the clutch to the fonnsprag clutch component for distortion 3

. Check main rotor dampers , disassembling the damper from the cage and performing polishing if any wear is notices as a groove or detent. 4. In spect blades visual l y with at least lOX glass fo r cracking of the skin at the rivet locations at the leading edge s par or hinge root block 5. If cracks are noticed wh ich are questionable after revievv ing the manufacturers maintenance publications, perform an eddy current inspection of th ese questioned areas. 6. I nspect for any "overload" based stress wrink les in the blade skin s adjacent the hinge root block area of stress concent ration and if limits exceed those in the manu fa cturers maintenance publication s, remove the blade fi·om service until properly repaired by an FAA Approved Repair Station with authority to perform blade repairs or re-sk inning in accordance with approved proces s specif ications. Any findings should be reported in th e FAA Service Difficult y Reporting System with full details and the manufacturer shou l d be notified in writing with photographs ofthe damage round and resu lts ofthe above in spections. How they justify it: The AD is premature. There hasn't been appropriate research or analysis to determine there i s an unsafe condition; and the root cause is not clearly identified. Many defects cited as unsafe conditions in the NPRM are all owed per the ori g inal maintenance and overhaul manuals. The propo sed changed practices/ inspections to the SAIB will stop t he b l ade skins t-J·om cracking or delaminat ing li·om the foam core due to random overload events and improper operation. Note: While we wer e sti ll operating a flight school pulling over 200 hours per month on Brantly B2B's. we noticed that in the newly manuf.1ctured ones, the outboard hinge plates were not properly manulaclured as it relates to alignment of the attachme nt ha r dware s upp011ing the flapping hinge bearings and b l ocks. This caused premature bearing wear. chaffing. and interferenc e which re sulted in vibrations not normal for a Brantly. I notitied the facto ry ofthe issue, with drawings and dimen s ions and photos ofthe premature wear at about 120 hours total time; and they reportedl y found a pr oblem an d fixed it. FAA Response: We partially agree. We agree with allowing some imperfections (See Issue: Allow Some Imperfections). We disagree with issuing an SA IB because the FAA has data that supports that an unsafe condition ex ists and that it must be addressed with an AD. SAIBs only prov i de information and do not mandate the needed actions to correct the unsafe condition. We a lso disagree that the AD is premature because the FAA has adequate information to make its determinations. The root cause of the failures has been demonstrated by Brantly, the TC ho lder, with help !Tom a laboratory report written by a metallurgical engineering company. That report concluded that the M /R blades failure was caused by hydrocarbon contamination in side the blades skin

-to

-foam bond and t hat the rracture originated near the trai li ng edge. We d isagree that Brantly 's original maintenance and overhau l m anuals adequately address the un safe condition. (See Issue: Replace the AD). We also disagree with the following contents !Tom the proposed SAIB: 1. On a one time basis for tho se helicopters where s uch an inspection has not been documented ; remove the outboard blades and inspect the outboard main rotor hinge for binding, chaffing at the outboard flapping hinge bearings and condition ofthe attachment hardware.Brantly M/R Blade AD, Docket No. FAA-20 12-1093, Disposition of comments:

2. Inspect the main rotor lag damper for delamination , chaffing ofthe metal plates with the damper cage , and polish any grooves in the inside diameter ofthe damper cage smooth to stop inadvertent loss of damping action ; and reassemble the damper and cage assemb ly. 3. Inspect the damper attachment lugs (threaded portion) to ensure it is not hitting the trailing edge blade cross section and if so, grind the end slightly to ensure clearance when properly adjusted in accordance with the manufacturers rigging instructions. 4. Weigh each main rotor blade (outboard) and compare static weights. If any blade is more than 2 ounces different, contact a service facility which can match balance the blades using the approved method. 5. Once blades are match balanced, reinstall them and rig them in accordance with the manufacturer's maintenance manual. 6. Dynamically balance the main rotor system using an ACES or Chadwick or similar system until the vibration is below .08 ips (it is possible with properly matched and rigged blade systems to achieve levels as low as 0.01 ips from a hover to Vne). Repetitive Inspections: I. On a daily basis, perform a tap test in accordance with the original Brantly Maintenance Publications, checking for any evidence of delamination ofthe skin to the foam core. 2. At the Annual Inspection for low utilization personal aircraft and at each I00 hour inspection for aircraft used in flight training or commercial operations of higher utilization , visually check the rivet areas at the leading edge spar and hinge block for deformation and cracking, following the limits published in the original Brantly maintenance publications. Special Inspections: After any overload event such as a "Quick Start" or " hard landing" or failure to bottom the collective below 250 rotor rpm, perform the following special inspections: I. Inspect main rotor centrifugal clutch area for dust and clean out with compressed air 2. Check attachment ofthe clutch to the fonnsprag clutch component for distortion 3. Check main rotor dampers, disassembling the damper from the cage and performing polishing if any wear is notices as a groove or detent. 4. Inspect blades visually with at least lOX glass for cracking ofthe skin at the rivet locations at the leading edge spar or hinge root block 5. If cracks are noticed which are questionable after reviewing the manufacturers maintenance publications, perfonn an eddy current in spection ofthese questioned areas. 6. Inspect for any "overload" based stress wrinkles in the blade skins adjacent the hinge root block area of stress concentration and if limits exceed those in the manufacturers maintenance publications, remove the blade from service until properly repaired by an FAA Approved Repair Station with authority to perform blade repairs or re-skinning in accordance with approved process specifications.Brant ly M/R Blade AD, Docket No. FAA-2012-1093, Disposition of comments: Any findings should be reported in the FAA Service Difficulty Reporting System with full details and the manufacturer should be notified in writing with photographs ofthe damage found and results ofthe above inspections. We disagree with these proposed SAlB contents becaus e no supporting data has been provided that shows that the proposed changed practices/inspections to the SAIB would stop the blade skins from cracking or delaminat ing from the foam core because ofrandom overload events and improper operation. Also , no supporting data has been provided that showed that an improper manufactured or installed hinge block caused the unsafe condition

. We also disagree with changing the inspections required in the AD as prescribed because the proposal eliminates the necessary eddy current inspection and reduces the IOx magnifying glass inspection (See Issue: Reduce Inspection Requ i rements) , and permits delamination that are too large, (See Issue: Allow Some Delamination), which is required to correct the unsafe condition.