A basic requirement for any aircraft electrical system should be an annunciator panel to immediately notify the pilot that something is wrong with his aircraft. There's nothing like a big red or yellow lamp to catch a pilot's attention to something that needs attention. Unless the pilot is made immediately aware of a failure, there is no way that timely action can be taken.

Unfortunately, in the Grumman Tiger there is no type of failure annunciator panel. The only notice a pilot gets of failure comes from taking an active look over at the engine gauges. Unfortunately, these gauges are placed well over to the extreme right side of the panel, well out of the normal scanning. A little needle quavering way off to the side out of peripheral vision just doesn't cut it.

Adding a failure annunciation panel is a very easy and straightforward addition to any aircraft. The primary systems in a non-complex aircraft that demand failure annunciation include:

1. Low voltage/alternator failure
2. Low oil pressure
3. Low fuel pressure
4. External power applied to aircraft

If we have been making updates to the aircraft as described in previous sections, we already have two of these requirements already covered. In the section on ground power, we designed a system that would illuminate a lamp any time external power is applied to the airframe. In the section on the voltage regulator we noted that the LR3B has provisions for a lamp to provide the pilot with information that his electrical system has malfunctioned. Providing lamps for low oil and fuel pressure are almost just as easy.

Tiger N81140 is equipped with engine gauges from Mitchell Aircraft Products. The electrical engine oil and fuel pressure gauges receive their signal from pressure transducers in the pressure lines. These transducers can easily be replaced with units that are virtually identical, except with the addition of a normally closed circuit. This NC circuit can be wired to lamps on the dash panel to warn the pilot of low fluid pressures.

These warning lamps would use simple circuitry and common aviation electrical components. Simple lamp bulbs and sockets would be used. No push-to-test lamps would be required, because when the aircraft is at rest with the master switch on during preflight, all lamps will be illuminated by design. The overvoltage circuit will have a separate push-to-test for the overvoltage protection features.

An example of the annunciation panel is illustrated in Figure 9.