U.S. Department of Transportation 

Docket Operations

West Building, Room W12-140

1200 New Jersey Avenue, SE

Washington, D.C. 20590-0001

June 21, 2013

Re: Petition for Exemption, 14 CFR § 25.571(e)(1), Project ODA-2328-01, Installation of the Aircell Broadband 

Services (ABS) System with Ku Enhancements on Airbus A320 Family Aircraft

In accordance with 14 CFR Part 11, Star Aviation hereby petitions for an exemption from 14 CFR § 25.571(e)(1) 

(Amendment 25-86) as it relates to the above referenced certification project. For the reasons detailed below, Star 

Aviation requests an immediate exemption from this rule and that it remain valid for a period of one year from the date 

of STC issuance. 

Star Aviation has been contracted by Gogo, LLC. to perform engineering and certification services on Gogo’s behalf. As 

such, some of the information contained in this letter is based on relevant data that has been performed by or on behalf 

of Gogo’s current Ku Supplemental Type Certificate (STC) programs or pertains to the commercial impact as it would 

affect Gogo, LLC.

Safety and Public Interest

The petition would not adversely affect safety because of the extremely low probability of a bird strike as summarized 

below. This radome and similar radome types are currently installed on following aircraft types:

Airbus: A319, A320, A330, A340

Boeing: BBJ, 737, 747, 767, 777

McDonnell Douglas: MD-87

This service experience further demonstrates an additional margin of safety. Moreover, the aircraft's frontal fuselage 

shadows the Ku Band radome due to the aircraft's angle of attack during all but the most extreme flight operations. 

Additionally, we have substantial service information from Delta Airlines that identifies 127 Airbus A330 and Boeing 767 

Series Aircraft which have over 500,000 accumulated hours throughout 2012, including over 30,000 hours below 10,000 

feet, without any bird strikes to a radome, which is detailed below in bird strike substantiation section of this document. 

Additionally, similar radome is in service with Live TV for over 13 years and close to 10 million flight hours without a bird

strike occurring.

1

Radome Design

The design of the Ku Band radome is an aerodynamic shape, similar to previous designs, with minimal height. It is 

located on the crown of the fuselage and aft of the wing spar to reduce the aerodynamic influence on the original 

airframe. This location ensures that a bird strike event will not occur throughout the aircraft's normal flight operations 

due to the aircraft's angle of attack (AOA). In addition to these physical characteristics the radome incorporates 

engineering advances in composite materials and lessons learned based on previous installations.

Star Aviation chose the radome design, its location on the aircraft and method of compliance for 14 CFR § 25.571(e)(1) 

over 9 months ago. The current project, ODA-2328-01, began in September 2012. The Project Specific Certification 

Plan was submitted on October 10, 2012. The actual installation design data is in its final stages of completion. ODA2328-01 certification project requires successful completion of project number SA08072CH-T.

 1 In the matter of the petition(s) of LIVETV for an exemption from §25.571(e)(1) of Title 14, Code of Federal Regulations, Regulatory 

Docket Nos. FAA-2013-0336, FAA-2013-0338, FAA-2013-0372, FAA-2013-0373 (United States Department of Transportation, Federal 

Aviation Administration May 9, 2013).
Bird strike substantiation

In the final rule preamble for § 21.101 (the changed product rule) the FAA acknowledged the importance of determining 

the certification basis for changed aeronautical products in a timely manner:

The type certificate applicant needs to know, early in a certification program, what the applicable airworthiness 

standards will be in order to finalize the detailed design of its product and to enable the applicant to make 

reasonable performance guarantees to its potential customers. (65 FR 36246, June 7, 2000)

Completion of STC project #SA08072CH-T is required for the successful completion of the above referenced project. 

The design data package for the project that was submitted to the FAA Chicago ACO included a Bird Strike report. DER 

approval for this report was granted with a limitation of maximum speed of 250 knots below 10,000 ft. per normal 

operating conditions. This limitation is in accordance with normal operating procedures for Boeing 767-300 series 

aircraft. All approvals along with additional reports were provided to the ACO on 02/05/13.

Chicago ACO approached Transport Airplane Directorate (TAD) to seek guidance regarding the limitation as identified 

in the Designated Engineering Representative’s (DER’s) approval. Transport Airplane Directorate clarified interpretation 

of the Issue Paper ruling from “normal flight envelope” to “normal design envelope.”

In 2009, EASA commissioned a study to evaluate the effects of bird strikes in an effort to determine the adequacy of the 

FAA’s certification requirements for bird strikes.

In the report, it was found that 96% of all bird strikes (which were statistically 186 per million flight hours for transport 

category aircraft) occur in the takeoff, climb, approach and landing phase. No surprise since these are the phases of 

flight that normally occur below 10,000, during which time all transport aircraft in the United States are operationally 

restricted to airspeeds of 250 KIAS or less.

The same report found that only 9% of all Part 25 bird strikes resulted in damage (including engines) and only 0.3% of 

the strikes involved kinetic energy above the required certification values.

Below is the data provided by Delta Air Lines for their 2012 fleet: 

AIRCRAFT 

TYPE 

A/C w/ 

LARGE 

ANT. 

ACCUM. HOURS ACCUM. CYCLES BIRD STRIKES 

(total/radome) 

APPROX. 

EXPOSURE TIME 

BELOW 10,000 FT

A330 32 143,353 18,105 35/0 7,242 

767 95 391,632 57,067 176/0 22827 

This is only one year’s worth of data however the airline reports that they have never experienced a bird strike on a top 

fuselage mounted radome. In addition to the Airbus A330 and Boeing 767, they operate significant numbers of Boeing 

737 and 757 aircraft with large antenna installations.

A review of the actual bird strike data provided by the airline shows that the overwhelming majority of bird strikes 

occurred in the landing and rollout phase of flight. It further shows that damage to the fuselage and wings is extremely 

rare. The data appears very consistent with the conclusions of the EASA study.

A teleconference was held between Gogo, Envoy, FAA Chicago ACO and Transport Airplane Directorate on 02/11/13.

FAA determined that additional substantiation was required to show compliance to 14 CFR § 25.571(e)(1). 
Based on recommendation from TAD, Bird strike simulation analysis was performed by Gogo. Results showed the 

following:

• Bird penetrates radome

• Brackets holding the antenna fail and antenna starts to move back, inside the radome

• Antenna comes to rest inside the radome after 100msec

• Antenna is contained inside the radome and does not depart the radome

This report was reviewed by TAD and the Chicago ACO. TAD asked that following be performed to substantiate the 

analysis:

• Validation of model that was created for analysis through a physical test

• Impact Loads analysis, to see effects of ram air inside the radome

• Effect on aircraft structure

• Conclusion – bird strike testing must be conducted if radome is exposed during any phase of flight for all aircraft 

weights and speeds up to and including cruise velocity, Vc

Since the meeting with TAD and ACO, Gogo has conducted a physical bird strike test and performed several analysis. 

This additional analysis has been quite intensive and involved a substantial effort from Gogo, our vendors for this 

project, as well as our airline partner, Delta Airlines. However, additional time is needed to continue to evaluate and 

substantiate the Ku radome design for full 14 CFR § 25.571(e)(1) compliance. 

International operations

The operators of U.S.-registered aircraft who have contracted with Gogo for the ABS System with Ku enhancements

design installed routinely fly to Europe, Asia, etc. The Ku Band satellite system is expected to operate in the same 

regions. Therefore, in accordance with 14 CFR § 11.83, Gogo requests this exemption apply to both domestic and 

international operations.

As the State of Registry for most of the aircraft on which the modification will be installed the FAA will continue to be 

responsible for the airworthiness and continued airworthiness of these aircraft wherever they operate. 

Commercial Impact

Gogo is incurring significant material costs as a result of the delay in obtaining approval of satellite system installation 

on American Air Lines Airbus A320 series aircraft.

Good Cause Exists to Issue the Exemption without Notice and Comment

Star Aviation requests that the FAA issue the exemption without publication for comment in the Federal Register.

Section 14 CFR § 11.87 lists four factors considered by the agency in deciding whether a petitioner has shown good 

cause for the FAA not to delay action on the petition. Those factors are set forth below in bold italics along with the 

company's response in plain text:

(a) Whether granting the petition would set a precedent: 

According to the FAA's exemption data base, fourteen exemptions have been granted to 14 CFR § 25.571(e)(1). 

Additionally, the FAA has permitted aircraft to operate for a limited period of time pending the installation of required 

modifications to address a compliance issue discovered late in the certification process.
(b) Whether the relief requested is identical to exemptions previously granted: 

The relief requested in this petition is different from ten out of the 14 of the other grants of exemption from 14 CFR § 

25.571(e)(1) in which applicants requested an exemption to use 0.85 Vc at 8,000 feet rather than Vc from sea level 

to 8,000 feet as the rule required at that time. The relief requested in this petition is identical to the remaining four 

exemptions in which the applicant requested an immediate exemption to the rule itself. 

(c) Whether delaying action would adversely affect Gogo: 

In light of the importance of the Ku band project to Gogo's core business, the rapidly changing technology involved 

in this modification, the project's advanced stage, and the disruptions to operators that have contracted for the Ku

Band system, delaying action on the petition would adversely affect Gogo

(d) Whether the petition was filed in a timely manner: 

The petition is timely filed. Gogo has had frequent discussions on this subject with the Chicago ACO and the 

Transport Airplane Directorate for the last several months.

In light of the above considerations Star Aviation submits that good cause exists not to delay action on this request.

Summary of Exemption Request

In accordance with 14 CFR § 11.81(f), Gogo offers the following summary suitable for publication in the Federal 

Register in the event the FAA believes that good cause to waive publication has not been established.

Star Aviation petitions the FAA for an exemption from the discrete source damage tolerance (i.e., bird strike) 

requirements of 14 CFR § 25.571(e)(1) for a period of one year based on data that such a bird strike encounter is less 

than extremely improbable.

Please feel free to contact me if you need further information. 

Respectfully,

Garland E. Borowski, PE

Engineering Manager

Star Aviation, Inc.

gborowski@staraviation.com

(251) 650-0600