(The following is a page on working out ship repair details within the Firefly 'verse in such a way as to be more cogent and useful for a roleplaying game. Those who do not find such interesting will... probably continue to not find this interesting.)
"The universe is made of stories, not atoms."
Every component of a vehicle ceases to function at some point or another. Weapons fire can hit sensitive equipment. Bugs in software can run a part out of factory specs. Poor maintenance, carelessness and neglect can push parts to a premature old age. Radiation and bombardment by solar and atmospheric winds will eat through anything, given time. Reckless piloting can overload even the best components.
But that's not interesting. People's cars break down all the time -- no one writes novels about changing a tire unless there's a real story there. So, the question is: when is a broken part a good story?
Surely, it can happen (one of the best episodes in Firefly revolves around a broken part, after all (Out Of Gas). Even 'minor damage' to a vehicle or ship can be interesting; it may mean that only the cooling system is damaged, so there's no immediate threat, but it can become important later. An attack that barely penetrates the hull might just knock out some minor backup systems and not impair any functions... for the time being.
So let's say that we've got a story to tell, and it involves something interesting happening around a broken part. That's where the real story begins: usually, this means finding a replacement (which is easier than repair).
From planetside vehicles to starships, scrounging mechanics will encounter a laundry list of components with brand names, popular names, and slang attached to them. Every vehicle moves different substances around within itself to function and/or provide environmental control for its occupants; this is true as much today as it is in the 'verse: you can find examples of almost all combinations of tables 2, 3, and 4 within a modern automobile (with a few notable sci-fi exceptions). The point of all this is to be able to provide you with ideas of components so they can better be described, which lets everyone get more involved in the story of the thing.
Below are instructions for using several tables to determine broken parts the the difficulty of replacement. For a much simpler list, see the page on Ship Troubles.
When a part is damaged, roll on Table 1 to determine the importance of the component. Roll once each on tables 2, 3, and 4 to determine the exact nature of the part that must be replaced or repaired. Each result carries a modifier to scrounging up a replacement (or the parts needed to fix it), except Table 1; its modifier is handled by the size of the component (see below for details).
Table 1: Importance and/or Size (roll 1d6)
Table 2: Scrounging modifiers due to Component (roll 1d6)
Table 3: Purpose of Part (roll 1d10)
Table 4: Scrounging Modifier from Component
These tables are arranged in order of complexity/size so that one could more easily estimate a price and rarity for a replacement. A suitable/compatible replacement "small air drain pipe" is logically simpler to find than a "large plasma processing pump."
Scrounging will be invaluable in finding these components. Calculate the entire part's difficulty to be scrounged (the next modifier from all four tables), and modify this by the population and technology level where the part is being scrounged to represent the chance of the part being available or easily manufactured wherever you are. After all the knowns are tallied, add additional penalties or bonuses if the part itself is rare in this area (such as trying to find old Firefly parts at an Alliance-run supply base).
Example: The Juggled Goose, a large transport, has lost its Primary Pressure Cooling Sensor near a small colony of 50,000 people. Although this is a 'primary' part, the GM rules that the part is small (Size Mod -5%). On his own, the mechanic would have a -5% (main), -10 (high pressure gas), +0 (Cooling), +5 (Sensor), -10 (small colony with low tech), +5 (part size) for a total of -15% penalty to Scrounging.
This is all scaled for a private civilian trying to access possibly dangerous technology. For individuals who are part of corporations or military units using official channels, the hunter must roll against Administration. A "professional" scrounger will then use his own Scrounging roll, modified by the Administration success and the perceived need of the part. Signatures from higher-ups can act as increased Money Offered.
Scrounging is the skill of locating items, and it is then up to the group's negotiator to acquire it. Also, once a component is located a successful Mechanics skill roll is required to assess the current quality of the item. The local value of a component increases with the size and complexity (e.g. higher table numbers) but decreases the more common an item is, and also decreases with a higher bulk demand (because of greater mass production). To perform the actual maintenance or repairs, use mechanics.
How Not To Put Out A Fire
Once a component is damaged, it may catch on fire. It may spread the damage over to nearby parts if the fire is not contained properly. Electrical fires (from overloads) should only be extinguished with inert gas or dry chemicals. Ordinary fires (wood, paper, cloth) should be stopped with only foam, water, and dry chemicals. Flammable liquids can be extinguished by any of the above except water, which helps spread the fire.
There are a couple of concerns that must be addressed with respect to the different fire suppression systems. The first is that if a system uses anything other than inert gas (CO2, halon) there is a mess to clean up that may interfere with equipment and create navigation/work hazards. The second is that if an inert gas system is used sufficiently to quench a fire, then it has replaced all the oxygen in that area. This means that any air-burning device (or person) in the immediate area will choke, suffocating until the air can be replaced (from seconds to minutes). Air-breathing components will keep running until they "choke," and then just stop working instead of taking damage (as a person would). Safety provisions could be put in place to prevent the suffocation of crew members in the area. On the other hand, if there is a crew member in the area and that prevents an extinguisher from activating, the fire will continue to burn unhindered. This is one reason why many combat-oriented starship crews don space suits and depressurize the ship at the first sign of combat -- there's fewer decisions to make.