' Surdex Geospatial Systems Integration, LLC 

203 Airport Drive, Hangar 6 

Westminster, MD 21157 

tel 800-847-6459 

fax 410-391-1767 

www.surdexsgsi.com 

August 12, 2011 

Ms. Brenda D. Courtney 

Manager, Aircraft and Airport Rules Division 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591 

Dear Ms. Courtney, 

Chuck King 

Director of Maintenance 

chuckk@surdexgsi.com 

In response to your June 30, 2011 letter for a request for additional information, Docket #FAA2011-0534 and your extension for our response to August 18, 2011, please accept this letter as an 

addendum to Surdex Geospatial Systems Integration's (SGSI) original request dated May 10, 

2011 for exemption as defined by 14 CFR 125.3(a), from 14 CFR 125.226(b)(2) for three ATR42-320 aircraft. 

In your request for information letter, you indicated we must send the following information to 

meet the requirements of 14 CFR Part 11.81: 

1. The reasons granting the request would be in the public interest: that is, how it would 

benefit the public as a whole. 

2. Any more information, views, or arguments to support the request. 

SGSI believes it is in the public's interest to grant the exemption for the following reasons: 

1. The three aircraft have been safely operated since 1991 without the additional 

parameters. Adding these parameters through an extensive aircraft modification program 

will not enhance public safety. SGSI operates the aircraft to conduct geological survey 

services with a crew of six company employees. SGSI does not carry passengers or 

cargo. 

2. Parameters (a) .12, 13, and 14 do not enhance aircraft safety, airworthiness, or handling 

qualities since they record flight control inputs for data collection only. Primary flight 

controls are mechanical and their position is continually monitored and recorded. 

3. The aircraft OEM does not support upgrading the Flight Data Acquisition Unit (FDAU) 

to add the additional parameters since it is no longer in production. SGSI has not found 

any possible solution to upgrading the FDAU before February 2012. 
Surdex Geospatial Systems Integration, LLC 

203 Airport Drive, Hangar 6 

Westminster, MD 21157 

tei80D-847-6459 

fax 410-391-1767 

www.surdexsgsi.com 

Chuck l<ing 

Director of Maintenance 

chuckk@surdexgsi.com 

In the event our request for an exemption is denied, SGSI would respectfully request a temporary 

extension to the LODA expiration of February 2012 to February 2013 in order to modify all 

three aircraft to meet the required FOR parameters and allow SGSI adequate time to plan for 

upgrading the FDAU and FDR via STC or OEM development of a service bulletin. SGSI's 

business plan would consist of approximately 12 months of engineering development and 

approximately 6 months for modifications. 

In closing, this request is not intended to disregard the Federal Aviation Regulation, but to 

continue to operate with an equivalent level of safety. The current FDR system records 39 

parameters, but does not record required flight control inputs. However the system records the 

required flight control surface positions. Since the flight control systems are mechanical and 

there are no hydraulic or electronic controls, it would impossible for the surface and control to be 

in different positions other than a break in the control circuit. We feel this allows for an 

equivalent level of safety. In addition, it is noted that our operation provides aerial survey 

services and only carries crewmembers, never passengers. Please contact me if you have any 

questions. 

Sincerely, 

Chuck King 

Director of Maintenance