P.O. Box 700548, Dallas, Texas 75370-0548 

(972) 725-9000  FAX (972) 725-9090 

U.S. Department of Transportation 

Docket Operations 

West Building Ground Floor, Room W12-140, 

1200 New Jersey Avenue, SE., 

Washington, DC 20590. 

February 19, 2013 

Subject Petition for Exemption from 121.1115 

Model: B-737-200 Advanced 

S/N: 22732 

Line#: 877 

This letter is a request for an exemption from 14 CFR Part 121.1115 

A. Name and Address of the Petitioner 

Ameristar Air Cargo, Inc, dba Ameristar Charters 

4400 Glenn Curtiss Drive 

Addison, Tx 75001 

B. Section of the Code of Federal Regulations (CFRs) that are Affected 

14 CFR part 121.1115 Amendment. 121-351 (121.1115) 

Where it states in part: 

“Limit of validity. No certificate holder may operate an airplane identified in paragraph (a) of this 

section after the applicable date identified in Table 1 of this section unless an Airworthiness 

Limitations section approved under Appendix H to part 25 or § 26.21 of this chapter is 

incorporated into its maintenance program.” 

C. The Extent of Relief Being Sought 

Ameristar respectfully requests it be allowed to continue to operate one specific aircraft, a Boeing 

737-200 Advanced, N733TW and Boeing Serial Number 22732 (N733TW) listed in Paragraph 

D085 of its current Operations Specifications. 

D. Why Relief is Being Sought 

Ameristar is requesting relief from the existing rule due to the fact that Boeing just recently 

(January 2013) indicated that they would not support the engineering data to substantiate a Limit 

of Validity (LOV) beyond that called out in the FAA’s final rule – Docket ID FAA-2006-24281 (See 

Figure 3 page 69768). Ameristar depended on Boeing to continue to support its aircraft to 

comply with the Limit of Validity (LOV). If Ameristar had known that Boeing would not support its 

aircraft, it would have attempted to find an alternative aircraft and begin the process of placing the 

new aircraft on its certificate. Boeing’s decision to discontinue its support of Ameristar’s aircraft 

coupled with the amount of time it would take to find a replacement aircraft and place that aircraft 

on its certificate is improbable in the time left stated in the rule. In addition, Ameristar believes 

that the rule specifically considered that low utilization aircraft, such as N733TW, would not be 

required to comply with the 121.1115. 
Exemption Request from 14 CFR Part 121.1115 Page 2 February 18, 2013 

E. Description of the Issue 

The rationale for 121.1115 is to prevent Widespread Fatigue Damage (WFD) to a metallic 

structure when the structure is subjected to repeated loads, such as the pressurization and 

depressurization that occurs with every flight of an airplane. Over time this fatigue damage 

results in cracks in the structure, and the cracks may begin to grow together. WFD is the 

simultaneous presence of fatigue cracks at multiple structural locations that are of sufficient size 

and density that the structure will no longer meet the residual strength requirements of Sec. 

25.571(b). 

Ameristar understands that the primary intent of 121.1115 was to amend FAA regulations 

pertaining to certification and operation of transport category airplanes to prevent widespread 

fatigue damage in those airplanes. For certain existing airplanes, the rule requires design 

approval holders to evaluate their airplanes to establish a limit of validity of the engineering data 

that supports the structural maintenance program (LOV). Design approval holders and applicants 

must demonstrate that the airplane will be free from widespread fatigue damage up to the LOV. 

The rule requires that operators of any affected airplane incorporate the LOV into the 

maintenance program for that airplane. 

F. Arguments 

Ameristar currently operates its B737-200 in a niche market serving primarily college teams and 

private charters within the contiguous U.S. on an ad hoc basis. The data and information below 

describes the utilization, maintenance schedules and current state of N733TW. 

1. This aircraft has a very low utilization rate with a current “C” Check interval of 24 months. 

The following times substantiate this low utilization: 

Total Flight Hours Since September of 2005: 2511 

Total Cycles since September of 2005: 1495 

Yearly average hours: 334 

Yearly average cycles: 199 

Hours Flown February 1, 2012 through February 1, 2013 332 

Cycles per year February 1, 2012 through February 1, 2013 215 

In context, this means that a “C” check is conducted with less than 800 flight hours and 450 

cycles. This is approximately 26% of the hours and 23% of the cycles that would be 

expected in a normal “C” Check with a scheduled air carrier. The FAA’s NPRM, dated April 

18, 2006, Docket FAA-2006-24281 page 19934, indicates more of concern for the 

scheduled carriers vs an aircraft with low utilization, such as Ameristar’s B-737, where it 

states: 

“...the group of airplanes of most concern is that group operating under parts 121 

and 129. Because carriers in scheduled operations fly airplanes operated under 

those parts, they are flown more often than other airplanes of comparable size 

and are accordingly more likely to develop WFD. Thus, this proposal would 

exclude airplanes over 75,000 pounds that are not operated under parts 121 or 

129...” 

2. The Boeing Company – Submitted an Anticipated Limit of Validity Data for the B737-200 of 

85,000 cycles and 100,000 hours. See letter to Docket FAA-2006-24281-0084, dated 

march 23, 2009. 
Exemption Request from 14 CFR Part 121.1115 Page 3 February 18, 2013 

3. In the Final Rule (Docket FAA-2006-24281 beginning at page 69750) previous aircraft 

incidents and accidents that involved WFD were discussed, specifically: 

a. April 1988, when an 18-foot-long section of the upper fuselage of a Boeing Model 737 

airplane separated from the airplane during flight. The airplane, operated by Aloha 

Airlines, was en route from Hilo to Honolulu, Hawaii, at 24,000 feet. At the time of the 

accident, the airplane had accumulated 89,680 flight cycles and 35,496 flight hours. 

Contrasted with Ameristar’s aircraft that is well below the Aloha’s number cycles and 

is also below the number of hours and cycles in Boeings anticipated LOV. Aloha’s 

operation in an exclusively salt water rich environment, coupled with the lack of 

maintenance programs that exist today (See Paragraph F.5. below, Ameristar’s 

aircraft is not even remotely in the same category as this accident aircraft. 

b. References to aircraft found with WFD along a lap joint (a B727 and B-737) is also 

not representative of Ameristar’s aircraft since there are no longer suspect lap joints 

on the aircraft due to compliance with AD 2002-07-08, incorporating Boeing SB 737-

53A1177. 

4. Ameristar’s B737 has had no major alterations to the original design – no doors, windows, 

cargo doors/floors, no increase in design ZFW, Gross weight or other initial operating 

conditions from original design. 

5. Ameristar’s B737 has been subject to numerous maintenance programs and repetitive 

Airworthiness Directives that are directly related to the promulgation of 121.1115. These 

repairs, inspections and programs include: 

a. A Corrosion Prevention and Control Program (CPCP), based on Boeing document# 

D6-38528, is in place to comply with the intent of AD 90-25-01 for inspection 

procedures, compliance times and reporting requirements. 

b. An Aging Aircraft Inspection accomplished July 10, 2007. Repetitive due July 2014. 

c. Compliant with the Repair Assessment Guidelines. Based upon Boeing document 

D6-38669 and mandated by FAR 121.1107, this program is in place to repetitively 

inspect structural areas of the fuselage pressure boundary. 

d. Compliant with the Structural Significant Inspection Program (SSIP) mandated by AD 

98-11-04 for the required Damage Tolerance Rating (DTR) for each Structural 

Significant Item (SSI) listed in Boeing document D6-37089. 

e. Compliant with the Damage Tolerance Assessments for repairs and/or alterations to 

Primary Structural Elements (PSE’s) of the aircraft structure. 

f. All required repetitive Non-Destructive Testing (NDT) is current. 

 

6. Current status of aircraft 

a. Boeing factory lap joints required repair/termination by AD 97-22-07 (superseded by 

AD 2002-07-08) in accordance with Southwest Airlines Aircraft Change Order# 7143-

53, based on Boeing Service Bulletin 737-53A1177. 

b. Suspect lap joints at S-4L and S-4R were removed from the aircraft structure between 

body stations 360 and 908. Fillers were installed with doublers and triplers installed 

on top of the fillers, joining the upper and lower skin panels. 

c. Suspect lap joints at S-10L, S-10R, S-14L and S-14R were removed from the aircraft 

structure between body stations 360 to 540 and 727 to 908. Fillers were installed with 

doublers and triplers installed over the fillers, joining the upper and lower skin panels. 

7. N733TW is not routinely operated in a rich salt water environment such as coastal and offshore areas. 
Exemption Request from 14 CFR Part 121.1115 Page 4 February 18, 2013 

G. Statement of Public Interest 

Ameristar provides service in a niche market that is well suited for this specific aircraft and at a 

cost and benefit to those customers that it serves. Ameristar can continue to provide existing 

customers an aircraft at prices that they expect and reliable service that this aircraft has provided 

them. It is also in the public interest to provide service on an aircraft that is operated under the 

highest standards of 14 CFR Part 121 vs. this aircraft being operated under 14 CFR part 1251

(Part 125) with a similar amount of hours and cycles that Ameristar currently operates on a yearly 

basis. N733TW, if this exemption is approved, would continue to be inspected and maintained 

under all of the current programs, stated in Paragraph F.5. of this petition, providing inspection 

intervals, in relationship to cycles and hours, at a fraction of those of aircraft operated by 

scheduled carriers. 

H. Statement of No Adverse Effect on Safety 

The data presented in this petition strongly suggests that there would be no adverse effect on 

safety and in fact would provide a wider margin of safety for the following reasons: 

1. Due to the low utilization of this aircraft, both cycles and hours, the intervals for major 

inspections is significantly less than envisioned in the NPRM and final rules for Part 

121.1115. This is consistent with the FAA’s own analysis of low utilization aircraft such as 

those aircraft operated under the authority of Part 125 in a non-scheduled environment. 

2. The Department of Transportation’s and FAA’s current position allows a Part 125 air 

operator to serve numerous customers2

. If this exemption is not granted, Ameristar would 

more than likely sell this aircraft to a Part 125 air operator. The introduction of service for 

this aircraft by a Part 125 air operator will lessen the FAA oversight, decrease the number 

of regulatory layers and overall decrease the level of safety currently required by operation 

of this aircraft under 14 CFR Part 121. Allowing the requested relief, will maintain the 

current levels of safety that are currently in place with this aircraft. 

3. Low cycles and utilization compared with a scheduled carrier or even an all-cargo carrier 

that flies consolidated freight. 

4. Ameristar would propose that this exemption, if approved, would limit it to no more than 500 

hours and 300 cycles in any calendar year. 

I. Summary of Petition 

Ameristar respectfully requests that this petition for exemption be approved based upon the 

foregoing information. 

J. Request for Reduced Comment Period 

Due to the time sensitive nature of this request, Ameristar respectfully requests that the public 

comment period be kept as short as permissible. 

 

1

 14 CFR part 125 operators are not required to comply with the LOV, do not require the management structure of 

a 14 CFR Part 121 air carrier, no economic authority required, significantly less FAA surveillance, no drug 

program, no restrictions on pilot age, limited flight and duty time restrictions (can fly over 8 hours in a duty period), 

pilot and flight attendant training requirements are significantly less stringent, and operational control procedures 

are also significantly less. 

2 See DOT’s The Role Of Air Charter Brokers In Arranging Air Transportation, dated October 8, 2004 

http://www.dot.gov/airconsumer/Role-of-air-charter-brokers

.
Exemption Request from 14 CFR Part 121.1115 Page 5 February 18, 2013 

K. Privileges of this Exemption Outside the United States 

Per the requirements of §11.83, Ameristar requests that the relief granted by this exemption 

remain in effect for operations outside of the United States to include those areas of operations 

specified in its Operations Specifications Paragraph B050 (North America, South America, 

islands in the Gulf of Mexico and the Caribbean. 

Your consideration of this exemption petition is greatly appreciated. 

Sincerely 

Pat Hulsey 

Director of Operations 

Ameristar Air Cargo, Inc.