FINAL REGULATORY EVALUATION 

FATIGUE TOLERANCE EVALUATION OF METALLIC STRUCTURES 

(14 CFR Part 29.571) 

OFFICE OF AVIATION POLICY AND PLANS

AIRCRAFT REGULATORY ANALYSIS BRANCH, APO-3O0

George A. Euring, Jr.

March 16, 2011
TABLE OF CONTENTS

 Page

I. Introduction......................................................................................1

II. Background......................................................................................2

III. Benefits...........................................................................................4

IV. Costs.............................................................................................10

V. Benefit-Cost Comparison.....................................................................17

APPENDIX A: Existing and Final Rule Comparison

List of Sources
1

REGULATORY EVALUATION OF FATIGUE TOLERANCE 

EVALUATION OF METALLIC STRUCTURES

I. INTRODUCTION

This regulatory evaluation assesses the economic impact of a final rule amending Part 

29.571 of Title 14, Code of Federal Regulations (14 CFR) to modify the regulations applicable to 

transport category metallic rotorcraft structure. This final rule will revise the fatigue tolerance 

evaluation (FTE) safety requirements to address advances in structural fatigue substantiation 

technology for metallic rotorcraft structure. The FAA received 3 comments from Transport 

Canada on the Notice of Proposed Rulemaking (NPRM). None of these comments required a 

change from the regulatory evaluation conclusions. Therefore, the initial regulatory evaluation 

becomes the final regulatory evaluation. 

This final regulation is the result of information gathered from a review of catastrophic 

fatigue failures, and is intended to improve the level of safety. The final rule will ensure that,

should serious accidental damage occur during manufacturing or within the operational life of 

the rotorcraft, the remaining structure can withstand fatigue loads that are likely to occur, without 

failure, until the damage is detected or a part is replaced. 

In addition to improving the level of safety for FTE of all principal structural elements 

(PSE), this final rule will more closely harmonize Federal Aviation Administration (FAA) 

standards with requirements of the European Aviation Safety Agency (EASA). 
2

II. BACKGROUND

A. Introduction

Fatigue of rotorcraft dynamic components was first addressed in the 1950’s by means of 

safe-life methodology. In the 1980’s, it was recognized that higher levels of reliability might be 

realized by taking into account the fatigue strength reducing effects of damage that can occur 

during manufacture or in operational service. 

The introduction of composites led the manufacturers and regulatory authorities to 

develop a robust safe-life methodology by taking into account the reducing effects of aging, 

temperature, moisture absorption, impact damage, and recognition of a minimum quality

standard on the specific static and fatigue strength. Furthermore, where clearly visible damages 

resulted from impact or other sources, inspection programs were developed to maintain safety. 

In parallel, crack growth methodology has been successfully used for solving short-term 

airworthiness problems in metallic structures of rotorcraft and as the certification basis for civil 

and military transport aircraft applications. 

These advances in design, analytical methods, and industry practices made it feasible to 

address certain types of damage that could result in fatigue failure. The general understanding of 

rotorcraft fatigue tolerance evaluation has developed considerably in the past several years, 

making possible the more advanced techniques described in this final rule. 

B. Rulemaking Prior To This Proposal

The most recent rulemaking, prior to this final rule, started in 1982 and resulted in the 

current rule, Amendment 29-28. There has not been any other rulemaking activity in this area 

since 1989 when Amendment 29-28 became effective (54 FR 43930, October 27, 1989. There 
3

have been no ADs issued as a result of this rule. There has been only one aircraft certificated 

under Amendment 29-28, the Sikorsky S-92. 

C. The Aviation Rulemaking Advisory Committee (ARAC-2000):

The FAA requested that the Aviation Rulemaking Advisory Committee (ARAC) study

the need to revise the applicable regulations on fatigue evaluation in light of advancements in 

technology and operational procedures and to develop regulatory recommendations. Following a 

notice published in the Federal Register on April 5, 2000 (65 FR 17936), an ARAC Working 

Group was chartered to study and make appropriate recommendations concerning whether new 

or revised airworthiness standards were appropriate regarding fatigue evaluation of transport 

rotorcraft metallic structure. 

The ARAC is composed of 76 member organizations with a wide range of interests in the 

aviation community and provides the FAA with firsthand information and insight regarding 

proposed new or revised rules. The ARAC established working groups to develop 

recommendations for resolving specific airworthiness issues. 

In response to the FAA’s tasking of April 5, 2000, ARAC’s Rotorcraft Metallic Structure 

Damage Tolerance Working Group developed recommendations addressing changes to the 

fatigue evaluation requirements for transport rotorcraft found in 14 CFR §29.571 to improve 

currency and understanding. The ARAC accepted those recommendations and presented them to 

the FAA. This final rule is based on those recommendations. 
4

III. BENEFITS

A. Introduction

In the absence of a new rule, it is likely that future metallic fatigue-related accidents will 

continue to occur on part 29 rotorcraft in a manner similar to what has happened in the past. A 

key benefit of this final rule will be the avoidance of these accidents. 

This chapter discusses the number of metallic fatigue related accidents in part 29 

helicopters for the historical 27 year study period 1982 through 2008. The costs of these 

accidents are then estimated and projected into the future for 27 years. This study period was 

chosen because the NTSB Accident Database starts in 1982 and 2008 was the latest year for 

which, at least, some data was available when this study was prepared. The costs of these 

preventable accidents that will occur without this final rule are the benefits of this final rule 

because we believe that this final rule will prevent at least some of these future avertable 

accidents. 

The benefits of this final rule were also estimated for the shorter, ten year period 1998 to 

2008. 

B. Historical Accidents

The FAA reviewed historical metallic fatigue related accidents for part 29 helicopters for 

the 27 year period 1982 through 2008. In the review of the accident history, the FAA considered 

only accidents that were relevant to metallic rotorcraft structural fatigue problems and that might 

have been prevented if this rule had been in effect. In addition, the FAA did not consider events 

in which externally aggravating circumstances existed, such as operation of the aircraft outside 

of its weight and balance limitations. To obtain this history we examined the NTSB Aviation 
5

Accident Database & Synopses and the Aviation Safety Information Analysis and Sharing 

System (ASIAS) databases. 

Table B1 shows that between 1982 and 2008, there were 9 metallic structural fatigue 

related Transport Category Rotorcraft accidents. The FAA believes that these 9 accidents could 

have been prevented if this rule had been in effect. 

These accidents resulted in 7 fatalities, 3 serious injuries and 3 minor injuries. In 

addition, all of the aircraft involved in these accidents were either destroyed or received 

substantial damage.1

Table B1A shows the same information for the time period 1998 to 2008. During this 

period there were 2 metallic structural fatigue related Transport Category Rotorcraft accidents. 

The FAA believes that both these accidents could have been prevented if this rule had been in 

effect. 

These accidents resulted in 3 fatalities and one serious injury. In addition, both of the 

aircraft involved in these accidents were destroyed. 

 

1 National Transportation Safety Board (NTSB) Accident Reports, FAA Aviation Safety Information Analysis and 

Sharing (ASIAS).
6
7

C. Current Dollar Market Value of Historical Accidents

We calculate the costs of a future averted accident in order to quantify future benefits. 

The minimum value of a statistical aviation fatality avoided is set at $5.8 million, that of a 

serious injury (assumed to be the average of a severe, serious, and moderate injury) at 

$1,122,700, and that of a minor injury at $82,800. The associated medical and legal costs are 

included in the injury costs. In addition, the average replacement cost of a destroyed turbine 

rotorcraft greater than or equal to 7,000 pounds equals $2,303,000, the restoration costs are 

estimated to be $470,000 and NTSB accident investigation costs about $45,000.

2

 

 

2

“Economic Values for FAA Investment and Regulatory Decisions, A Guide.” (GRA Incorporated, Final Report, 

Revised October 3, 2007); “Aviation Accident Investigation Costs,” (FAA APO Bulletin, August 2000). 
8

Table B2 shows the economic value assigned to the historical losses listed in Table B1. 

The total cost of these 9 accidents is estimated to be approximately $58 million and the average

cost of one of these accidents is estimated to be approximately $6.4 million. 

Table B2A shows the same information for the two accidents that occurred between 1998 

and 2008. The total cost of these 2 accidents is estimated to be approximately $23.2 million and 

the average cost of one of these accidents is estimated to be approximately $11.6 million. 
9

D. Present Value Benefits

The present value benefit estimate assumes that the probability of an accident is equally

likely in any year of the 27-year study period (Uniform Distribution). 

If the final rule were to be 100% effective, 9 accidents will be avoided over the next 27

years and, the present value benefit of avoiding these accidents will be approximately $25.4

million. 

If the final rule were to be 56% effective, 5 accidents will be avoided over the next 27 

years and, the present value benefit of avoiding these accidents will be approximately $14.1 

million. 

If the final rule were to be 22% effective, 2 accidents will be avoided over the next 27 

years and, the present value benefit of avoiding these accidents will be approximately $5.6 

million. 

If the final rule were to be 11% effective, 1 accident will be avoided over the next 27 

years and, the present value benefit of avoiding this accident will be approximately $2.8 million. 

See Table B3. 
10

Table B3A presents the same information for the 10 year period 1998 to 2008. 

The present value benefit estimate assumes that the probability of an accident is equally

likely in any year of the 10-year study period (Uniform Distribution). 

If the final rule were to be 100% effective, 2 accidents will be avoided over the next 10 

years and, the present value benefit of avoiding these accidents will be approximately $16.3 

million. 

If the final rule were to be 50% effective, 1 accident will be avoided over the next 10 

years and, the present value benefit of avoiding this accident will be approximately $8.2 million. 
11
12

IV. COSTS

A. Introduction

This final rule will add costs to rotorcraft manufacturers and operators. Rotorcraft 

manufacturers will be required to conduct additional actions in the certification process. The

final rule will require additional inspections for rotorcraft operators. These incremental costs 

will be estimated in the remainder of this chapter. 

We assign certification costs in the first year for each new decade. The operator 

inspection costs increase as the new production helicopter fleet increases. We did not estimate 

the life cycle costs (and benefits) because we do not have reliable information on helicopter endof-service time. For this analysis we let the fleet accumulate without retiring any of the new 

production helicopters. 

B. Rotorcraft Manufacturer Incremental Costs

1. Incremental Certification Actions

The final rule will require rotorcraft manufacturers to take the following additional

actions in the certification process: 

1) perform a more thorough threat assessment, and submit a threat assessment

 methodology report to the FAA for approval;

2) perform a more rigorous residual strength assessment; 

3) include both retirement times and inspection intervals in the Airworthiness Limitation 

 Section (ALS) of the Instructions for Continued Airworthiness (ICA). 

The rotorcraft manufacturers currently perform a threat assessment and a residual 

strength assessment in the certification process. However, these assessments will become more 

robust under this final rule and consequently add costs. 
13

The current rule mandates that manufacturers must establish inspection intervals or

retirement times. This final rule mandates that both retirement times and inspection intervals 

must be included in the airworthiness limitation section of the Instructions for Continued 

Airworthiness, thereby increasing costs. Appendix A provides a chart comparing the current rule 

to this final rule. 

2. Number of Certifications

There are currently three transport category helicopter manufacturers in the United States, 

Bell (A wholly owned subsidiary of Textron, Inc.), Sikorsky (A subsidiary of United 

Technologies Corporation), and Erickson Air-Crane, Inc.. Two of these manufacturers, Bell and 

Sikorsky, expect to obtain new transport category helicopter type certificates in the future. 

Representatives from Bell and Sikorsky estimate there will be one new type certificate 

every 10 years for each of their companies. These estimates result in a total of 2 new transport 

category helicopter type certificates every 10 years. The study period for this analysis is 27 

years. We front-load certification to the first year of each new decade. Therefore, it is assumed 

that there will be two new transport category helicopter type certificates in the first, eleventh, and 

twenty-first years of the study period, resulting in a total of six new transport category helicopter 

type certificates during the 27 year study period. 

3. Costs Per Certification

Based on information from industry representatives on the ARAC Working Group, we 

estimate that the average additional cost to perform a more thorough threat assessment will be 

$87,000 per certification; the average additional cost to perform the more rigorous residual 

strength assessment required by this rule will be an additional $43,500; and putting both 
14

retirement times and inspection intervals in the airworthiness limitation section of the 

Instructions for Continued Airworthiness will cost, on average, an additional $46,980. 

Based on information received from industry representatives, we also estimate that over 

the next 27 years, Part 29 rotorcraft structures will be comprised of approximately 50% metallic 

parts and 50% composite parts. Hence, the additional per certification cost under this final rule 

will be $43,500 for a threat assessment ($87,000 * 0.5 = $43,500), $21,750 for a residual 

strength assessment ($43,500 * 0.5 = $21,750), and $23,490 for putting both inspection intervals 

and retirement times in the airworthiness limitation section ($46,980 * 0.5 = $23,490).

Therefore, we estimate that the total certification cost per new type certification will be $88,740 

($43,500 + $21,750 + $23,490 = $88,740). Table C1 below shows a summary of the average 

cost per certification. 
15

C. Rotorcraft Operators Costs

In addition to the incremental costs to rotorcraft manufacturers for aircraft certification, 

this final rule will increase the rotorcraft operator’s costs by requiring additional inspections. 

Industry representatives on the ARAC Working Group estimated that approximately 30 

components will require additional inspection as a result of this final rule, and that it will take a 

mechanic one hour to inspect each component. Therefore, an inspection will take 30 man-hours. 

Based on an aviation mechanic’s wage rate of $53 per hour, each inspection will cost 

approximately $1,600 (30 man-hours X $53 per hour = $1,590). 

Based on information received from industry representatives, we estimate that 

inspections will occur, on average, approximately every 1,250 flight hours. In order to estimate 

the number of years between inspections, it is necessary to determine the approximate number of 

hours that a transport category helicopter might fly in a year. Table C2 shows that, from 2000 -

2007, turbine rotorcraft flew an average of 387 flight hours annually. (FAA Aerospace 

Forecasts, Fiscal Years 2008-2025, p. VI-3; p. 86) Therefore, inspections will occur, on average,

about once every 3 years (1,250 / 387 = 3.22) during the 27 year study period. 
16

D. Total Costs

1. Introduction

The total costs of the final rule consist of certification costs and inspection costs. 

Certification costs are a one time cost borne by the manufacturer for each new type certificate. 

Inspection costs are a recurring cost (every three years) borne by the operators. 
17

2. Total Certification Costs

For cost estimation purposes, we assume that the new models will be certificated in years 

1, 11, and 21, during the 27-year analysis period, and that each future aircraft certification will 

have a production run of 10 years. 

The total undiscounted cost of six certifications during the 27 year analysis period is 

approximately $532,000. The total present value cost, at a 7% discount rate, for six certifications 

during the 27 year analysis period is about $293,000. 

3. Total Inspections Costs

The total inspections cost depends upon the cost per inspection and the number of aircraft 

produced. The cost per inspection has been estimated above at $1,600. 

The forecasted production rates for a new Sikorsky model is based on the first four years 

of production of the Sikorsky S-92 (2004-2007). In the fourth year of production of the S-92, 

Sikorsky produced 29 S-92’s. This number is used as a forecast for the fifth through tenth year 

of production. 

During the 2004-2007 period Bell’s production of transport category rotorcraft was 

approximately the same as Sikorsky’s. Therefore, we assume that Bell’s production rate for a 

new model will be equal to Sikorsky's. 

We estimate that the total inspections costs over the 27-year analysis period will be 

approximately $8.5 million in undiscounted costs or about $2.6 million in present value costs

over 27 years. 

D. Total Incremental Costs 

The total cost of this final rule over 27 years is estimated to be approximately $9.0 

million in undiscounted costs or about $2.9 million in discounted costs. 

Table C3 shows the calculation of the total costs of this final rule. 
18
19

V. BENEFIT COST COMPARISON

A. Benefits

The benefits of the final rule are the value of the accidents that may be averted by the 

final rule during the next 27 years. The estimated present value benefits range from a minimum 

of $5.6 million if one accident is prevented during the next 27 years to a maximum of $25.4 

million if 9 accidents are averted. 

B. Costs

The costs of the final rule are the additional costs for manufacturers to prepare a more 

thorough certification process and the costs for operators to conduct additional inspections. The 

present value costs of this final rule are estimated to be $2.9 million. 

C. Benefit Cost Comparison s

Table BC1 shows a comparison of the benefits and costs of the final rule with both the 

benefits and the costs estimated for the 27 year study period. 

Table BC1 shows that the present value benefits of the final rule exceed the present value 

costs of the final rule if the final rule averts as few as two accidents in the next 27 years. The 

FAA Rotorcraft Directorate estimates that the final rule will be at least 50 percent 

(approximately 5 accidents) effective at preventing the identified past 9 accidents which could 
20

happen in the future. However, the final rule is still cost beneficial if it is as little as 22% 

effective. Therefore, the present value benefits of the final rule exceed the present value costs of 

the final rule. 

Table BC2 shows a comparison of the benefits and costs of the final rule with the benefits 

estimated for 10 years and the costs estimated for the 27 year study period. 

Table BC2 shows that the present value benefits of the final rule exceed the present value 

costs of the final rule even when the benefits are estimated for ten years and the costs are 

estimated for the full 27 year study period. The FAA Rotorcraft Directorate estimates that the 

final rule will be between 50 percent (1 accident) and 100 percent (2 accidents) effective at 

preventing the identified past 2 accidents which could happen in the future. Therefore, the 

present value benefits of the final rule exceed the present value costs of the final rule. 
1

Appendix A: Existing and Final Rule Comparison

Existing Rule 29.571: Fatigue Evaluation of Structure

(Part 29 Subpart C – Strength Requirements)

Final Rule 29.571 Fatigue Tolerance Evaluation of Metallic 

Structure.

(a) General. An evaluation of the strength of principal elements, 

detail design points, and fabrication techniques must show that 

catastrophic failure due to fatigue, considering the effects of

environment, intrinsic/discrete flaws, or accidental damage 

will be avoided. Parts to be evaluated include, but are not 

limited to, rotors, rotor drive systems between the engines and 

rotor hubs, controls, fuselage, fixed and movable control 

surfaces, engine and transmission mountings, landing gear, and 

their related primary attachments. In addition, the following 

apply:

(a) General. A fatigue tolerance evaluation of the principal 

structural elements (PSEs) identified in paragraph (c) below 

must be performed and appropriate actions established, as 

defined in paragraph (g), to avoid catastrophic failure during the 

operational life of the rotorcraft. This evaluation must consider 

the effects of both fatigue and the damage determined in 

paragraph (d)(3) below. Parts to be evaluated include, but are 

not limited to, rotors, rotor drive systems between the engines 

and rotor hubs, controls, fuselage, fixed and movable control 

surfaces, engine and transmission mountings, landing gear, and 

their related primary attachments.

(1) Each evaluation required by this section must include –

(i) The identification of principal structural elements, the 

failure of which could result in catastrophic failure of 

the rotorcraft.

(ii) In-flight measurement in determining the loads or

stresses for items in paragraph (a)(1)(i) of this section 

in all critical conditions throughout the range of 

limitations in Sec. 29.309 (including altitude effects), 

except that maneuvering load factors need not exceed 

the maximum values expected in operations; and

(iii) Loading spectra as severe as those expected in 

operation based on loads or stresses determined under 

paragraph (a)(1)(ii) of this section, including external 

load operations, if applicable, and other high frequency

power cycle operations.

(b) The compliance methodology must be submitted to the 

regulatory authority for approval.

(2) Based on the evaluations required by this section, inspections, 

replacement times, combinations thereof, or other procedures must 

(c) Considering all structure and/or structural elements and 

assemblies, the PSEs must be identified. PSEs are 
2

be established as necessary to avoid catastrophic failure. These 

inspections, replacement times, combinations thereof, or other 

procedures must be included in the airworthiness limitations 

section of the Instructions for Continued Airworthiness required 

by Sec. 29.1529 and Section A29.4 of Appendix A of this part.

structural elements that contribute significantly to the 

carrying of flight or ground loads and the fatigue failure of 

which can lead to catastrophic failure of the rotorcraft.

(b) Fatigue tolerance evaluation (including tolerance to flaws).

The structure must be shown by analysis supported by test 

evidence and, if available, service experience to be of fatigue 

tolerant design. The fatigue tolerance evaluation must include the 

requirements of either paragraph (b)(1), (2), or (3) of this section, 

or a combination thereof, and also must include a determination of 

the probable locations and modes of damage caused by fatigue, 

considering environmental effects, intrinsic/discrete flaws, or 

accidental damage. Compliance with the flaw tolerance 

requirements of paragraph (b)(1) or (2) of this section is required 

unless the applicant establishes that these fatigue flaw tolerant 

methods for a particular structure cannot be achieved within the 

limitations of geometry, inspectability, or good design practice. 

Under these circumstances, the safe-life evaluation of paragraph 

(b)(3) of this section is required.

(d) Each evaluation required by this section must include:

(1) In-flight measurement in determining the fatigue loads 

or stresses for the PSEs identified in paragraph (c) 

above in all critical conditions throughout the range of 

limitations in 29.309 (including altitude effects), except 

that maneuvering load factors need not exceed the 

maximum values expected in operations.

(2) Loading spectra as severe as those expected in operation 

based on loads or stresses determined under paragraph 

(d)(1) of this section, including external load operations, 

if applicable, and other high-frequency power-cycle 

operations.

(3) A determination for the PSEs identified in paragraph (c) 

above of the probable locations, types, and sizes of 

damage considering fatigue, environmental effects, 

intrinsic/discrete flaws, or accidental damage that may

occur during manufacture or operation.

(4) A determination of the fatigue tolerance characteristics 

for the PSEs with the damages identified in paragraph 

(d)(3) above to support accomplishment of paragraph 

(g) below.

(5) Analyses supported by test evidence and/or service 

experience.

(1) Flaw tolerant safe-life evaluation. It must be shown that the 

structure, with flaws present, is able to withstand repeated loads of 

variable magnitude without detectable flaw growth for the 

following time intervals--

(i) Life of the rotorcraft; or

(e) A residual strength determination is required to establish the 

allowable damage size. For inspection interval determination

based on damage growth, the residual strength requirement is 

limit load considered as ultimate.
3

(ii) Within a replacement time furnished under Section A29.4 of 

Appendix A to this part.

(2) Fail-safe (residual strength after flaw growth) evaluation. It

must be shown that the structure remaining after a partial failure is 

able to withstand design limit loads without failure within an 

inspection period furnished under Section A29.4 of Appendix A to 

this part. Limit loads are defined in Sec. 29.301(a).

(i) The residual strength evaluation must show that the remaining 

structure after flaw growth is able to withstand design limit loads 

without failure within its operational life.

(ii) Inspection intervals and methods must be established as 

necessary to ensure that failures are detected prior to residual 

strength conditions being reached.

(iii) If significant changes in structural stiffness or geometry, or 

both, follow from a structural failure or partial failure, the effect on 

flaw tolerance must be further investigated.

(f) The effect of damage on stiffness, dynamic behavior, loads 

and functional performance must also be considered.

(3) Safe-life evaluation. It must be shown that the structure is able 

to withstand repeated loads of variable magnitude without 

detectable cracks for the following time intervals--

(i) Life of the rotorcraft; or

(ii) Within a replacement time furnished under Section A29.4 of 

Appendix A to this part.]

(g) Based on the evaluations required by this section, 

inspections and retirement times or approved equivalent means 

must be established to avoid catastrophic failure. The 

inspections and retirement times or other means as applicable 

must be included in the airworthiness limitation section of the 

Instructions for Continued Airworthiness required by Section 

29.1529 and Section A29.4 of Appendix A of this part.

(h) If inspections for any of the damage types identified in part 

d(3) above, cannot be established within the limitations of 

geometry, inspectability, or good design practice, then 

supplemental procedures, when available, must be established 

that will minimize the risk of each of these types of damage 

being present or leading to catastrophic failure.
1

List of Sources

No. Source

1. Aastad, Andy, “So What’s the Fleet Count?”, ROTOR, Summer, 2003. 

2. ----------, “Active General Aviation Aircraft in the U.S. 1973-2007”, AOPA Online: Active 

General Aviation Aircraft in the U.S.,http://www.aopa.org/whatsnew/stats/aircraft.html, 

Accessed: 03/12/2009. 

3. Darby, Rick, U.S. “Helicopter Fatal Accidents Decrease Again”, AEROSAFETY WORLD, 

August 2008, FLIGHT SAFETY FOUNDATION

4. Downey, Dave & Rigsby, Matt, Analysis of U.S. Civil Helicopter Accidents, Presented to: 

Heli-Expo 2006, Safety Symposium, Federal Aviation Administration. 

5. ----------, Economic Values for FAA Investment and Regulatory Decisions, A Guide, Final 

Report, Revised Oct. 3, 2007, GRA Incorporated. 

6. ---------, FAA Aerospace Forecast – Fiscal Years 2008-2025. 

7. ---------, FAA Aviation Analysis and Sharing (ASIAS), Various dates. 

8. Fox, Roy, “IHST Metrics”, IHST Newsletter Issue No. 3, October 2008.

9. ----------, “Key Helicopter Statistics”, HAI 2009 Helicopter Annual

10. Lynch, Kerry, “Uncertainty Clouding Short-Term Plans For New Helicopters”, The Weekly

of Business Aviation, March 2, 2009. 

111. Mason, Karen, “Composites Take Off...In Some Civil Helicopters”, High Performance 

Composites, 03/01/2005. 

12. ----------, National Transport Safety Board (NTSB) Accident Reports, Various Years.

13. ---------, PHI Inc. 2007 Annual Report.

14. Royce, Douglas, “Rotorcraft Somewhat Stable”, Aviation Week & Space Technology

Aerospace Sourcebook, January 26, 2009. 

15. ---------, Treatment of the Economic Value of a Statistical Life in Departmental Analyses, 

U.S. Department of Transportation, February 5, 2008. 
2

List of Sources (Cont.)

No. Source

16. ---------, “U.S. Civil Helicopter Accidents, 10-Year Activity As A Percentage of Total 

Accidents, 1998-2007”, www.Rotor.com/portals/12/10%20yr.pdf, Accessed 

08/08/2008. 

17. ---------, U.S. Small Business Administration-Table of Small Size Standards Matched to 

North American Industry Classification System Codes, Effective August 22, 2008, 

http://www.sba.gov/size.