737 Tools · Annunciator Lights vs B737 Maintenance Mastermind

An annunciator light just came on. The call is yours. 737 Tools is a technical study and reference companion for 737 NG maintenance, built around that moment: understand the system, find the right box, work the fault — in the right order. Data is 737 NG. Many systems, lights and circuit breakers carry over to the 737 Classic and the MAX, so much of it applies there too — always confirm against the approved documentation for your specific aircraft. ANNUNCIATOR LIGHTS Every light by ATA chapter, with the full technical picture: • What triggers it and what clears it • Fault modes — the same light, different causes depending on switch position or configuration, each with its own path • Related circuit breakers, with panel and exact grid position • The LRUs involved • Related MEL items, with a clear NO DISPATCH warning • Your own field notes, saved on the light E/E TOUR — FIND THE COMPUTER Troubleshooting usually ends with a BITE test on a box you first have to find. The E/E Tour is a photographic walkthrough of the electrical/electronic compartment with every LRU marked on real photos of the bays. Tap a marker and you know the shelf and the neighbours before you open the hatch. CB panels are mapped the same way, each breaker pinpointed on the panel image. Pinch to zoom, double-tap to move in, swipe between bays. DAMAGE REPORTS Lightning strike inspections, hail, ground equipment contact — a dozen findings scattered across the airframe and a notebook full of loose photos. Create a report, add each finding with photos, location and measurements, keep them organised as one job, and export it as a PDF or ZIP from the aircraft. Paperwork you close out on the spot. COMMON PN Every line and hangar has its own short list of part numbers. Build your own catalogue: add each PN with photos and notes, organised by zone and category, and export your collection to share it with the team. ON THE RAMP • Fully offline — no signal needed at the stand or in the hangar • One search box across lights, LRUs, circuit breakers and part numbers • No account, no cloud — your notes, reports and PNs stay on your phone • Full backup to a single file, saved wherever you like TRAINING AND REFERENCE ONLY Designed for aircraft systems study and fault simulation. Information may not be current or fleet-specific and does not replace approved AMM, FIM, MEL or any official documentation — always work from the current approved manuals and your operator's procedures. Independent app, not affiliated with, authorised by or endorsed by any aircraft manufacturer.

B737 Maintenance Mastermind is an independent quick-reference and utility app designed to support aircraft technicians, engineers, mechanics, and aviation professionals working with Boeing 737 NG and MAX aircraft. The B737MM app combines fast offline tools with secure premium reference modules, helping users quickly find maintenance-related information, calculations, references, and troubleshooting guidance during study, training, planning, or daily technical routines. FREE TOOLS • MEL Calculator Quick helper for standard dispatch time limit calculations. • Unit Converter Fast conversion of common aviation units, including pressure, temperature, volume, weight, and fuel-related values. • Fuel Calculator Useful fuel uplift and density calculation tool for quick planning and cross-checking. • Abbreviations Dictionary Large searchable glossary of aviation, maintenance, and technical abbreviations. PREMIUM REFERENCE MODULES • Alerts Searchable cockpit alert, status, and message references with related technical context. • Flags Reference guide for PFD, ND, FMC/CDU, and display flags. • BITE Built-In Test Equipment reference module with test access information and related troubleshooting links. • MEL Reference Fast searchable Minimum Equipment List reference support for NG/MAX style workflows. • CDL Reference Configuration Deviation List reference module for missing or deferred aircraft configuration items. • Circuit Breakers / CB ATA-grouped circuit breaker reference with panel-related information. • Lights Cockpit, annunciator, and system light reference module with related system context. • Location Aircraft component, access panel, service panel, antenna, and equipment location references. • STA Map Station, frame, stringer, waterline, and aircraft location reference helper for quick orientation. • Visual Panels Interactive visual reference for cockpit panels and related light/panel locations. • Support & Materials Technical support notes, fastener/material references, practical troubleshooting notes, and maintenance helper information. PREMIUM ACCESS Premium reference modules open with an auto-renewable yearly subscription (with a 3-day free trial for eligible users) or a one-time lifetime purchase, both offered in the app. Payment is charged to your Apple Account at confirmation of purchase. The subscription renews automatically unless it is cancelled at least 24 hours before the end of the current period, and your account is charged for renewal within 24 hours before the end of the current period. You can manage or cancel your subscription in your Apple Account settings at any time after purchase. Use Restore Purchases in the app to restore access on a new device. Some premium content requires internet access for first download, access verification, or content updates. Once downloaded, content is available on the device for fast access. IMPORTANT DISCLAIMER This application is an independent reference and training support tool. It is not official Boeing documentation and is not affiliated with, endorsed by, sponsored by, or associated with The Boeing Company, any airline, aircraft operator, maintenance organization, or aviation authority. The information in this app is provided for educational, training, and general reference purposes only. The official Aircraft Maintenance Manual (AMM), Fault Isolation Manual (FIM), Illustrated Parts Catalog (IPC), Wiring Diagram Manual (WDM), Structural Repair Manual (SRM), and the operator-approved MEL/CDL are the only official sources and must always take precedence. Do not use this application as the sole source for aircraft maintenance actions, dispatch release decisions, operational decisions, or work on an actual aircraft. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://b737mm.com/privacy/