More info. verbatim   

All of the requirements for "Modern Aircraft" are here. They are specific to passenger carrying aircraft, not water/retardant only machines.

EXHIBIT 1 - MODERN HELICOPTER MINIMUM AIRCRAFT REQUIREMENTS
(a) Type 3
(1) Powerplant: Twin-turbine engine.
(2) Airspeed: 120 knots VNE at 5000 feet pressure altitude and 30°C at maximum gross weight.
(3) Seating: Utility seating configuration for six or more insured passenger seats not including pilot but including copilot seat in an aircraft if certificated for single pilot operation.
(4) Landing Gear: Skid type or wheeled.
(5) Certifications: Standard airworthiness certificate. Certificated as a 14 CFR Part 27 Normal Category or Part 29 Transport category aircraft that is certified for One Engine Inoperative operation, or a part 21.29 certified aircraft meeting the same standard. If not manufactured in the United States, only those aircraft certificated by a country the United States has a bilateral agreement with that incorporates reciprocal airworthiness certification of civil aeronautical products
(6) Systems: Integrated Aircraft Health and Usage Monitoring System, i.e., engine trend monitor, and vibration monitor systems in accordance with Attachment 33.
(7) Fuel Tanks: Crash Resistant Fuel System meeting at least partial compliance with Part 27.952 Amendment level 30 or 29.952 Amendment level 35. See SAIB SW-17-31R2 (or latest revision) for latest list of eligible aircraft
(8) Date of Manufacture: 2000 - Present.
(9) Aircraft in Current Production: The aircraft model derivative offered must be in current production, meaning the aircraft manufacturer is currently producing complete aircraft of the same model derivative offered.
161

1202SA22R9201
Helicopter Support Services (HSS)
United States Forest Service (USFS) National Interagency Fire Center (NIFC)
(b) Type 2
SECTION D
CONTRACT DOCUMENTS, EXHIBITS/ATTACHMENTS
(1) Powerplant: Twin-turbine engine.
(2) Seating: Utility seating configuration for minimum of six, maximum of nine insured passenger seats not including pilot but including copilot seat in an aircraft if certificated for single pilot operation.
(3) Landing Gear: Skid type or wheeled.
(4) Certifications: Standard airworthiness certificate. Certificated as a 14 CFR Part 29 Transport category aircraft that meets the criteria for Category A operation, or a part 21.29 certified aircraft meeting the same standard. If not manufactured in the United States, only those aircraft certificated by a country the United States has a bilateral agreement with that incorporates reciprocal airworthiness certification of civil aeronautical products
(5) Systems: Integrated Aircraft Health and Usage Monitoring System, i.e., engine trend monitor, and vibration monitor systems in accordance with Attachment 33.
(6) Fuel Tanks: Crash Resistant Fuel System meeting at least partial compliance with Part 29.952 Amendment level 35. See SAIB SW-17-31R2 (or latest revision) for latest list of eligible aircraft.
(7) Date of Manufacture: 2014 - Present.
(8) Aircraft in Current Production: The aircraft model derivative offered must be in current production, meaning the aircraft manufacturer is currently producing complete aircraft of the same model derivative offered.
162

1202SA22R9201
Helicopter Support Services (HSS)
United States Forest Service (USFS) National Interagency Fire Center (NIFC)
SECTION D
CONTRACT DOCUMENTS, EXHIBITS/ATTACHMENTS
(c) Type 1
(1) Powerplant: Twin-turbine engine.
(2) Airspeed: 130 knot indicated airspeed at 7,000 feet and 25 degrees C.
(3) Seating: Minimum of 10, maximum of 19 passenger seats that are insured. All seats shall meet a minimum TSO 39b with 3 point or more shoulder harness/ seat belts. All seats shall meet the requirements of Attachment
(4)Energy attenuating seats are preferred; Forward folding airline style seats are not acceptable. (i) OEM seating configurations are preferred.
(5)Flight Crew: Two pilots required. The SIC shall be type rated in the aircraft.
(6) Landing Gear: Skid type or wheeled.
(7) Certification: Standard airworthiness certificate. Certificated as a 14 CFR Part 29 Transport category aircraft that meets the criteria for Category A operation, or a part 21.29 certified aircraft meeting the same standard. If not manufactured in the United States, only those aircraft certificated by a country the United States has a bilateral agreement with that incorporates reciprocal airworthiness certification of civil aeronautical products
In addition to certifications required in B.2, contractors shall be certificated by the MAP start date of option year 2 to meet 14 CFR Part 135 for 10 or more passengers (less than 19 passengers). All passenger-carrying flights, regardless of the number of passengers carried, shall be conducted in accordance with the Contractor’s 14 CFR Part 135 operations specifications.
(8) Systems: Integrated Aircraft Health and Usage Monitoring System, i.e., engine trend monitor, and vibration monitor systems in accordance with Attachment 33.
(9) Avionics:
(ii) Internal PA System
(iii) PED Tolerance
(iv) Helicopter Manager Position:
(A) Aft Cabin Audio Controller
(B) Wireless drop cord in addition to the standard drop cord (C) Two USB ports
(D) Remote control of VHF-FM Radios
• Must include the ability to program all channel attributes, adjust sidetone, and adjust volume on all FM radios
Note: Audio drawings for Type 1 helicopters will be developed as part of the evaluation.
(10) Fuel Tanks: Crash Resistant Fuel System meeting at least partial compliance with Part 29.952Amendment level 35 are preferred. See SAIB SW-17-31R2 (or latest revision).
163

1202SA22R9201
Helicopter Support Services (HSS)
United States Forest Service (USFS) National Interagency Fire Center (NIFC)
SECTION D
CONTRACT DOCUMENTS, EXHIBITS/ATTACHMENTS
(11) Cabin Safety: Cargo/baggage storage and restraint system accommodates all passenger and firefighting equipment in accordance with aircraft certification and operator’s 135 certificate.
(12) Cargo compartments must comply 14 CFR Part 29.787 and 135.87. If approved in accordance with the aircraft certification and operator’s 135 certificate, cargo may be carried in the passenger compartments forward of the foremost seated passengers in accordance with the following:
(i) It is properly secured by a tie down having enough strength to eliminate the possibility of shifting under all normally anticipated flight and ground conditions.
(ii) It is packaged or covered in a manner to avoid possible injury to passengers.
(iii) It does not impose any load on the floor structure that exceeds the load limitation for floor loading.
(iv) Its location does not restrict access to or use of any required emergency or regular exit, or of the aisle in the passenger compartment.
(v) Its location does not obscure any passenger's view of required placards/ signs.
(13) Dual Aft cabin external doors used as primary entry and exit of the aft cabin
(14) Equipment: Type 1 Exhibit 1 aircraft shall provide an Initial Attack fully collapsible bucket not
weighing more than180lbs
(15) Hardpoint(s) for spotter tether attachment (Fall prevention device) of at least 2500 lb. minimum strength
(16) Date of Manufacture: 1990 - Present.
(17) Aircraft in Current Production: The aircraft model derivative offered must be in current production, meaning the aircraft manufacturer is currently producing complete aircraft of the same model derivative offered.
164