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Journal Article

Aircraft Electrical Power Systems and Nonlinear Dynamic Loads

Aircraft utilize electrical power for many functions ranging from simple devices such as resistive heaters to highly advanced and complex systems responsible for communications, situational awareness, electronic warfare and fly-by-wire flight controls. The operational states of these electronic systems affect safety, mission success and the overall economic expense of operation and maintenance. These electronic systems rely on electrical power within established limits of power quality. In recent years, electrical power quality is becoming excessively degraded due to increased usage of nonlinear and dynamic loads coupled to aircraft power systems that were neither designed nor tested for these loads. Legacy power generation systems were designed for electrical loads with resistive and inductive properties, which previously represented the majority of actual aircraft electrical loads.
Journal Article

Automated Fault Isolation of Intermittent Wiring/Conductive Path Systems Inside Weapons Replaceable Assemblies

Automated Fault Isolation of Intermittent Wiring/Conductive Path Systems Inside Weapons Replaceable Assemblies Wiring/conductive path faults inside Weapon Replaceable Assemblies (WRAs) that result in No Fault Found (NFF) or intermittent diagnosis are estimated to cost the DoD over $2B annually. To date there is no logistically supportable, standardized capability to reduce this annual cost. This report covers the development of this capability and its subsequent testing and fielding as a means to reduce this component repair costs. This new capability is called the Automated Wiring Test Set (AWTS) intermittent testing capability. To test the new capability, the F/A-18 APG-73 Radar Receiver (RR) chassis was selected due to its high repair cost and its #1 ranking as an avionics mission degrader for this type aircraft.
Technical Paper

Replacement of Sealed Nickel-Cadmium Batteries on Ch-53e and Mh-53e Aircraft with Sealed Lead-Acid Batteries

This paper will summarize the details of replacing the CH-53E and MH-53E crashworthy batteries to improve system reliability, safety of flight and to reduce battery maintenance and battery maintenance costs. A flight evaluation program is presently underway at Marine Corps Air Station (MCAS) New River, North Carolina to validate the proposed change from Sealed Nickel-Cadmium (SNC) batteries to Sealed Lead-Acid (SLA) batteries. Under the sponsorship of the Commander, Naval Air Systems Command the Crane Division, Naval Surface Warfare Center identified a SLA battery as a replacement for the SNC battery currently being used in the CH-53E and MH-53E aircraft. The replacement battery is a direct form, fit, and function replacement for the SNC battery. It is presently planned that the SLA battery will have a one-year inspection period and a replacement cycle of three years.
Technical Paper

Replacement of Nickel-Cadmium Battery on F-5 Aircraft with a Valve Regulated Lead-Acid Battery

In the continuing effort to save Fleet Operations and Maintenance (O&M) costs, a united effort was launched to propose the replacement of the Nickel-Cadmium battery on the F-5 aircraft with a valve-regulated, sealed lead-acid battery. The Aging Aircraft IPT (AAIPT) at Naval Air Systems Command, Patuxent River (PAX River), Maryland presented the concept to the Value Engineering group at Defense Supply Center Richmond, Virginia and successfully obtained funding for this and other Aging Aircraft efforts. The AAIPT then approached the Propulsion and Power Division of Naval Air Systems Command (AIR- as the cognizant engineering activity over batteries. AIR- then requested the assistance of Crane Division of Naval Surface Warfare Center (NSWC Crane) to develop a test plan and a Memorandum of Agreement and to obtain flight test authority as well as conduct the flight test.
Journal Article

Prismatic Li-Ion Cell for Unmanned Aircraft

Saft is working on advanced 28V Li-ion batteries for use in NAVY unmanned aircraft applications. This battery employs seven (7) prismatic state-of-the art Li-ion cells connected in series. The battery needs to be less than 40lbs in weight and 600 in3 in volume. This paper presents the performance results of the new prismatic cell. This development is pioneering new technological territories for SAFT since the PL55E cell is the first prismatic cell developed and delivered by SAFT America [1]. The experience gained will be useful and the PL55E cell will be followed by more prismatic cells added to the SAFT Li-ion portfolio. The presentation will give an overall status update of the technology as well as a brief overview of the complete 28V battery.
Technical Paper

Replacement of Sealed Nickel-Cadmium Batteries on EA-6B Aircraft with Valve Regulated Lead-Acid Batteries

This paper will summarize the details of replacing the EA-6B Sealed Nickel-Cadmium (SNC) batteries in an effort to reduce battery maintenance and battery maintenance costs. A flight evaluation program is presently underway at two locations to validate the proposed change from SNC batteries to Valve Regulated Lead-Acid (VRLA) batteries. The EA-6B aircraft currently uses two 26-volt SNC batteries, military part number (MIL PN) D8565/1-1, and one 24-volt SNC battery, part number MS17334-2. The SNC batteries are scheduled for maintenance every 112 days, which requires removal and replacement of the batteries at the O-level and battery maintenance at the I-level (battery shop). A load check is required every 28 days on the aircraft in accordance with the Maintenance Requirement Card (MRC).
Technical Paper

An Acoustic-Based Wiring Diagnostic System for Aircraft

An onboard Acoustic Wiring Diagnostic System to monitor the health of aircraft wiring is under development by Innovative Dynamics Inc. The AWDS incorporates passive acoustic sensors to monitor wire chafing. The system operates continuously in-flight so that intermittent wiring fault conditions can be detected as they happen. Trend analysis data can be logged to enable pro-active maintenance prior to catastrophic failure. A key advantage of the in-situ system is to perform the inspection without removing or disconnecting the wiring. Acoustic signatures of representative aircraft wiring have been characterized under simulated damage conditions. Flight ready hardware and software have been developed and flight testing is underway on an H-53 helicopter. This paper will present the wire diagnostic approach, the AWDS flight instrumentation, and some representative lab test results.