Sec. 171.323 - Fabrication and installation
(a) The MLS facility must be permanent
and must be located, constructed, and installed in accordance with best
commercial engineering practices, using applicable electric and safety
codes and Federal Communications Commission (FCC) licensing requirements
and siting requirements of §§171.313(b) and 171.317(b).
(b) The MLS facility components must
utilize solid state technology except that traveling wave tube amplifiers
(TWTA) may be used. A maximum level of common modularity must be provided
along with diagnostics to facilitate maintenance and troubleshooting.
(c) An approved monitoring capability
must be provided which indicates the status of the equipment at the site
and at a remotely located maintenance area, with monitor capability that
provides pre-alarm of impending system failures. This monitoring feature
must be capable of transmitting the status and pre-alarm over standard
phone lines to a remote section. In the event the sponsor requests the FAA
to assume ownership of the facility, the monitoring feature must also be
capable of interfacing with FAA remote monitoring requirements. This
requirement may be complied with by the addition of optional software
and/or hardware in space provided in the original equipment.
(d) The mean corrective maintenance time
of the MLS equipment must be equal to or less than 0.5 hours with a
maximum corrective maintenance time not to exceed 1.5 hours. This measure
applies to correction of unscheduled failures of the monitor, transmitter
and associated antenna assemblies, limited to unscheduled outage and out
of tolerance conditions.
(e) The mean-time-between-failures of
the MLS angle system must not be less than 1,500 hours. This measure
applies to unscheduled outage, out-of-tolerance conditions, and failures
of the monitor, transmitter, and associated antenna assemblies.
(f) The MLS facility must have a
reliable source of suitable primary power, either from a power
distribution system or locally generated. Adequate power capacity must be
provided for the operation of the MLS as well as the test and working
equipment of the MLS.
(g) The MLS facility must have a
continuously engaged or floating battery power source for the continued
normal operation of the ground station operation if the primary power
fails. A trickle charge must be supplied to recharge the batteries during
the period of available primary power. Upon loss and subsequent
restoration of power, the battery must be restored to full charge within
24 hours. When primary power is applied, the state of the battery charge
must not affect the operation of the MLS ground station. The battery must
allow continuation of normal operation of the MLS facility for at least 2
hours without the use of additional sources of power. When the system is
operating from the battery supply without prime power, the radome deicers
and the environmental system need not operate. The equipment must meet all
specification requirements with or without batteries installed.
(h) There must be a means for
determining, from the ground, the performance of the system including
antenna, both initially and periodically.
(i) The facility must have, or be
supplemented by, ground, air, or landline communications services. At
facilities within or immediately adjacent to controlled airspace, that are
intended for use as instrument approach aids for an airport, there must be
ground air communications or reliable communications (at least a landline
telephone) from the airport to the nearest FAA air traffic control or
communication facility. Compliance with this paragraph need not be shown
at airports where an adjacent FAA facility can communicate with aircraft
on the ground at the airport and during the entire proposed instrument
approach procedure. In addition, at low traffic density airports within or
immediately adjacent to controlled airspace, and where extensive delays
are not a factor, the requirements of this paragraph may be reduced to
reliable communications from the airport to the nearest FAA air traffic
control or communications facility. If the adjacent FAA facility can
communicate with aircraft during the proposed instrument approach
procedure down to the airport surface or at least down to the minimum en
route altitude, this would require at least a landline telephone.
(j) The location of the phase center for
all antennas must be clearly marked on the antenna enclosures.
(k) The latitude, longitude and mean sea
level elevation of all MLS antennas, runway threshold and runway stop end
must be determined by survey with an accuracy of ±3 meters (±10 feet)
laterally and ±0.3 meter (±1.0 foot) vertically. The relative lateral and
vertical offsets of all antenna phase centers, and both runway ends must
be determined with an accuracy of ±0.3 meter (±1.0 foot) laterally and
±0.03 meter (±0.1 foot) vertically. The owner must bear all costs of the
survey. The results of this survey must be included in the "operations and
maintenance" manual required by section 171.325 of this subpart and will
be noted on FAA Form 198 required by §171.327.
[Doc. No. 20669, 51 FR 33177, Sept. 18, 1986, as
amended by Amdt. 171-16, 56 FR 65665, Dec. 17, 1991]