ST Aerospace Mobile, Inc 

2100 9th Street, Brookley Complex 

Mobile, Alabama 36615, USA 

Tel : (251) 438 8888 

Fax : (251) 438 8892 

Singapore Technologies 

Engineering 

Page 1 of 8

FAA Atlanta 15th July, 2011 

Subject: Petition for Exemption 

Reference: FAA Project Number ST13005AT-T 

Dear Mr. Avella, 

ST Aerospace Mobile (STA Mobile) is the applicant for a multiple airplane Supplemental Type 

Certificate for conversion of Boeing 757-200 passenger airplanes into an “8 pallet/80-passenger” Combi 

configuration under FAA Project Number ST13005AT-T. STA Mobile expects issuance of STC by 

November 30, 2011. 

The purpose of this letter is to petition for an exemption from the requirements of certain sections 

of Title 14, Code of Federal Regulations (14 CFR), Part 25, to allow carriage of non-crewmembers, or 

‘supernumerary’ personnel, in a compartment aft of the flight deck on the converted airplanes. 

Supernumeraries will be restricted to those persons complying with § 121.583 (a)(1) through (a)(8). 

STA Mobile requests that the publication and comment procedures be waived in accordance with 

§ 11.29 and § 11.87 for the following reasons: 

i. Similar exemptions have been issued by the FAA for STC ST03562AT (STA Mobile 757-

200SF) 

ii. Granting this petition would not set a precedent 

DESCRIPTION OF CONVERSION 

The main deck of the Combi configuration consists of the flight deck, supernumerary area, main 

deck cargo compartment (MDCC) and a passenger cabin. The flight deck and supernumerary area is 

separated from the MDCC by a 9g Rigid Cargo Barrier (RCB) installed per STC ST02115LA at 

approximately STA 379. The passenger cabin is separated from the MDCC by a Smoke Barrier at 

approximately STA 1115. 

The supernumerary area will accommodate up to two supernumeraries as defined by § 121.583 

(a)(1) through (a)(8). The MDCC aft of the RCB is converted into a Class C cargo compartment, equipped 

with a Halon 1301 fire suppression system. The MDCC will be able to hold eight 88 x 125 or 88 x 108 
Singapore Technologies 

Engineering 

Page 2 of 8

sized pallets. The passenger cabin will be able to accommodate up to 80 passengers and 4 flight 

attendants. (See Figure 1). 

Figure 1: Main Deck Layout 

The Combi configuration retains Type I doors 1L and 1R, complete with escape slides or sliderafts. A rigid 9G barrier is installed just aft of door 1L, permitting both doors 1L and 1R to be used in an 

emergency evacuation. There is a sliding door on the left side of the RCB to provide access to the main 

deck cargo compartment. Two business class supernumerary seats are installed immediately forward of 

the RCB (See Figure 2). 

 
Singapore Technologies 

Engineering 

Page 3 of 8

Figure 2: Cabin Layout Diagram (Not to scale) 

The RCB is sealed to prevent smoke penetration. The two supernumerary seats are provided 

with supplemental oxygen through a salvaged passenger service unit with chemical oxygen generators 

and drop-down masks. Two-way communication is provided from the flight deck to each supernumerary 

seat through the relocation of an original flight attendant handset to the forward face of the RCB. 

This petition seeks relief from the requirements of the following sections of 14 CFR, for the Combi 

conversion: 

 § 25.785(j), Amendment 25-88,Seats, berths, safety belts, and harnesses 

 § 25.812(e), Amendment 25-128, Emergency Lighting 

 § 25.813(a) and (b), Amendment 25-128, Emergency Exit Access 

The following information is provided to support this petition: 

To date, STA Mobile has re-delivered forty (40) STA Mobile 757-200SF configured airplanes to 

Federal Express since the issuance of STC ST03562AT on April 2, 2008 and the supernumerary area 

layout design has accumulated a considerable satisfactory service history. 

In accordance with § 121.583, all persons that may be carried on the flight deck and 

supernumerary area will have special training, which includes proper methods for egress from the 

airplane and use of emergency equipments. Limitations will be imposed on the airplane operator to find 
Singapore Technologies 

Engineering 

Page 4 of 8

that all occupants of the supernumerary area are physically able to use the escape means provided. 

When supernumeraries are carried, they will be briefed prior to each flight as to the location and use of 

the emergency egress equipment, the supplemental oxygen equipment and the communication 

equipment. Supernumeraries are also prohibited from being in the cargo area during any flight operation. 

These limitations will be included as part of the Airplane Flight Manual Supplement (AFMS) similar to that 

of STC ST03562AT. 

The RCB sliding door will be closed and locked prior to taxi and will not be opened again for 

access to the cargo area until the airplane has parked at its destination. Steps will also be taken to 

ensure that no one is in the cargo area prior to the locking of the sliding door before taxi. Admission to the 

flight deck of the Combi-configured airplane will be limited to those people that meet the requirements of 

§ 121.547, "Admission to the flight deck." 

Occupancy of the flight deck and supernumerary area of the Combi-configured airplane is limited 

to a total of six (6) persons, which will consist of supernumeraries as defined by § 121.583 (a)(1) through 

(a)(8), and personnel permitted on the flight deck as defined by § 121.547. This limitation will be included 

in the AFMS similar to that of STC ST03562AT. The modification will include provisions to carry 

personnel as defined by § 121.547 in the supernumerary area in compliance with § 25.722(c). 

The Flight Crew Operations Manual Supplement (FCOMS) will provide instructions on the 

recommended evacuation procedures using doors 1L or 1R and the AFMS will include a requirement for 

the flight crew to brief supernumeraries on use of the escape provisions and communication equipments 

prior to each flight. 

§ 25.785(j), Amendment 25-88, “If the seat backs do not provide a firm handhold, there must be a 

handgrip or rail along each aisle to enable persons to steady themselves while using the aisles in 

moderately rough air.”

Justification: 

Hand holds are not available in the supernumerary area. The configuration of the supernumerary 

area with the seats’ backs positioned along the perimeter of the RCB as shown in Figure 2 does 

not permit using the seat back as the traditional handhold. The lack of handhold is identical to 

that of STA Mobile 757-200SF supernumerary area configuration. 
Singapore Technologies 

Engineering 

Page 5 of 8

A Petition for Exemption was submitted by STA Mobile in connection with the STA Mobile 757-

200SF with regards to the equivalent § 25.785(d) at Amendment 25-32, and this resulted in FAA 

Grant of Exemption No. 9487. 

The supernumerary area is limited to the use of operator assigned supernumeraries or flight crew 

(not public passenger) as described by § 121.583 (a)(1) through (a)(8) and/or § 121.547 whom 

have higher level of training and knowledge of the supernumerary area layout. There will also be 

a recommendation to supernumeraries to remain seated with their seat belts fastened. Therefore, 

an acceptable level of safety is provided. 

§ 25.812(e), Amendment 25-128, “Floor proximity emergency escape path marking must provide 

emergency evacuation guidance for passengers when all sources of illumination more than 4 feet 

above the cabin aisle floor are totally obscured.” 

Justification:

From Figure 2, the configuration of the converted Boeing Model 757-200 in the supernumerary 

area does not provide floor proximity emergency lightings, as required by § 25.812(e). 

The proximity of the two supernumeraries to the doors 1L and 1R, provides a level of safety that 

would not be enhanced by the installation of floor proximity emergency lightings. In addition, 

supernumeraries have a higher level of training and knowledge of the emergency exit layout than 

the typical passenger. Hence, the configuration of the supernumerary area provides an 

acceptable level of safety for the supernumeraries. 

§ 25.813(a), Amendment 25-128, “Passageways between individual passenger areas and those 

leading to Type I, Type II, or Type C emergency exits must be unobstructed and at least 20 

inches wide.”

Justification:

There are two Type I emergency exits located at the supernumerary area. However, the widths of 

the passageways between supernumerary seats and the Type I emergency exits fall short of the 

required minimum 20 inches at certain points. The point of the shortest passageway width, 

approximately 10.9 inches, is from the supernumerary seat to the edge of Lavatory A. 
Singapore Technologies 

Engineering 

Page 6 of 8

STA Mobile seeks to “de-rate” the two Type I emergency exits into Type III emergency exits. As 

such, the minimum 20 inches requirements in accordance with § 25.813(a) will no longer be 

applicable. Since the supernumerary area and the passenger cabin compartment are completely 

isolated from each other, STA Mobile affirms that the passenger seating configuration of the 

supernumerary area is inaccessible from the passenger cabin compartment aft of the smoke 

barrier. As such, there are only 6 occupants (including the flight crew) who will have access to 

Door 1L and 1R. 

The applicable regulation, § 25.813(c)(2)(ii) at Amendment 25-128 states that “For airplanes that 

have a passenger seating configuration of 19 or fewer, there may be minor obstructions in this 

region, if there are compensating factors to maintain the effectiveness of the exit.” The smaller 

passageway may be considered as a minor obstruction and the compensating factor would be 

the small number of supernumeraries and flight crew whom have a higher level of training and 

knowledge of the emergency exit layout than the typical passenger. Given that there are only two 

supernumeraries, there would not be any congestion in the passageways to the emergency exits 

during egress. In addition, the supernumeraries are in close proximity of the two Type I 

emergency exits. This is coupled with the fact that the supernumeraries are equipped with a 

higher level of knowledge of the airplane configuration than the typical passenger. Therefore, an 

acceptable level of safety is obtainable when the Type I emergency exits are “de-rated” as Type 

III emergency exits. 

§ 25.813(b), Amendment 25-128, “Adequate space to allow crewmember(s) to assist in the 

evacuation of passengers must be provided.”

Justification:

The configuration of the supernumerary area does not provide an assist space adjacent to each 

exit. However, since the supernumeraries will have a higher level of training than a typical 

passenger, they will have no need for crew assistance. In addition, in the relatively small confines 

of the supernumerary area, the flight crew can easily provide instructions and some physical 

assistance to the supernumeraries, if needed. 

The absence of an assist space adjacent to each exit is identical to the configuration of STA 

Mobile 757-200SF. A Petition for Exemption was submitted by STA Mobile for STA Mobile 757-
Singapore Technologies 

Engineering 

Page 7 of 8

200SF and resulted in FAA Partial Grant of Exemption (No. 9487). In Exemption No. 9487, The 

FAA had granted the exemption based on the same justifications described above. 

Evaluation of Public Interest: 

The presence of trained personnel on board the airplane when live or hazardous cargo is carried 

will enhance flight safety, which is in the public interest. 

Granting this exemption will enhance the utility of the airplane for the operator by ensuring that 

needed cargo management personnel will be available at each flight destination. This will reduce shipping 

costs, which is in the public interest 

As Boeing 757-200 passenger airplanes are converted into Combi-configured airplanes, airlines 

will replace them with new passenger airplanes which meet newer 14 CFR Part 25 Amendments. Over 

time, this will have the effect of raising the safety level of the passenger airline fleets, which is in the 

public interest. 

The usage of Combi-configured airplanes will optimize the space usage in flights in cases where 

there is a low demand in passenger flights and a high demand in cargo transportation. This will help 

reduce the number of flights and in turn lead to a reduction of air pollution, which is in the public interest. 
~:: ST Aerospace

A COnlpln'f at ST En9jl'l'-lflring

Petition for Exemption

Based on the information provided, STA Mobile, hereby petitions for exemption from the following

sections of 14 CFR Part 25 for Boeing 757-200 passenger airplanes converted to a Combi configuration

under FAA STC Project ST13005AT-T to allow the carriage of supernumeraries in the supernumerary

area aft of the flight deck:

• § 25.7850), Amendment 25-88

• § 25.812(e), Amendment 25-128

• § 25.813(a) and (b), Amendment 25-128

STA Mobile respectfully requests favorable FAA consideration of this petition.

Sincerely,

fATerence Tan

Engineering Director

ST Aerospace Mobile, Inc.

Office: (251) 436-0181

E-mail: Terence_TAN@stmae.com

Page 8 of 8 :-"'~ Singapore Technologies

'-111" Engineering