METS QandA_201208.pdf

Update: 8 December 2020

SOURCES SOUGHT NOTICE -- MULTI-ENGINE TRAINING SYSTEM (METS) AIRCRAFT PROCUREMENT Questions and Answers

Question (1): AV-051 is very general and unlikely every single inch of wire on the airplane is easily accessible for inspection/repair. Request the entity for this new shall requirement clarify and/or provide more specifics as to what they are requiring.

AV-

Reference: 3.1.9.3 Electric Power The METS electrical wiring shall permit inspection and repair.

NAVAIR Answer (1): Requirement AV-051 was generated to ensure the wiring system was sustainable throughout the life cycle of the aircraft. Verification of this requirement will be by inspection of an OEM standard wiring practices document. For example, the FAA AC 25-26 Development of Standard Wiring Practices Documentation provides guidance for developing an electrical system standard wiring practices document.

Question (2): AV-55 details the E-28 shore-based emergency arresting gear cable. Please attach details and specifications of the E-28 system to the beta.SAM notice.

AV-

Reference: 3.1.12 Landing Gear The METS landing gear shall permit taxiing over the E-28 shore-based emergency arresting gear cable.

NAVAIR Answer (2):

Deck Pendant:

The E28 deck pendant is a 1¼-inch-diameter, non-rotating wire rope with a polypropylene core, with swaged terminals on each end. It is typically 190-feet in length spanning the width of a 200-feet wide runway, but is available in longer length of 290-feet for wider runways.

Deck Pendant Supports:

The deck pendant for shore-based arrestments is required to be 2.5-5 inches above the surface of the runway, most commonly the cable will be 2.5-3.5 inches off the surface. This can be accomplished by using four methods of wire supports:

1) Most common is the rubber donut wire supports that are 7-inch-diameter, 2-inch width. These are pressed on to the cable over the swaged terminals.

2) Limited installs, but BAK-14 is the next most common support system. This is a USAF supported system that permits the cable to lower below the surface of the runway for heavy aircraft traffic. The cable is fixed into rubber blocks that permit release upon engagement for an arrestment. The blocks are attached to a mechanism that is also spring activated allowing the cable to depress below the runway surface during rollovers in addition to being fixed below the surface.

3) Cut aircraft tires, more often seen on expeditionary arresting gear systems, but can be utilized. Nose wheel tires cut into thirds with a slit on top to install the cable. If the slit is not done properly or the tire is installed incorrectly, the cable can come out during roller over and the tire become a hazard.

4) Polyurethane risers are permanently fixed to the runway when used with E28.

E28 General Description:

There are two arresting engines installed above deck on opposite sides of the runway. Each arresting engine operates a single nylon tape. The nylon tape from each engine is routed through a deflector sheave and a runway edge sheave assembly. The nylon tape is coupled to the deck pendant by means of a tape connector. The runway edge sheave assemblies are typically spaced at 225-feet apart when installed on a 200-feet wide runway.

During arrestment, the aircraft arresting hook engages the deck pendant, thereby causing the purchase tape to pay out and activate the arresting engines. As the purchase tape pays out, it rotates a tape drum connected to the vaned rotor

Update: 8 December 2020 within the arresting engine through a common shaft. The motion of the rotor creates hydrodynamic braking action, slowing the aircraft.

The T-44C has the following landing limitations/prohibitions related to the E-28 shore-based emergency arresting gear cable that may also apply to the METS aircraft:

1. Landing on arresting gear cable is prohibited.

2. Nosewheel contact with cable risers above taxi speed is prohibited.

3. Braking during cable rollover is prohibited.

4. Operation above taxi speed over arresting gear rigged with boots (tire segments) is prohibited.

Question (3): Can NAVAIR provide the mathematical definition and/or factors the Navy uses to compute the four rates in Table 3-3? Or since METS is a COTS aircraft solution, is NAVAIR agreeable to readiness rates calculated based on standard commercial aircraft industry calculations/metrics?

AV-

Reference: 3.2.1 Readiness The METS should achieve the readiness performance in Table 3-3.

NAVAIR Answer (3): The Government is agreeable to reviewing readiness rates calculated based on standard commercial aircraft industry calculations/metrics.