1. Leaky Hydraulic line
This nuisance that can cause pressure drops over time and interfere with the handing of the ship or the opening/closing of cargo doors/ramps. (The fluid could also short out some electronic equipment, or drip from an overhead crawl space onto the dinner table, someone's bunk, etc...)
2. Busted Circulation fan
Normally such fans are needed to keep the air fresh and nice smelling in areas of the ship. Until it's fixed one can expect certain stuffiness to the atmosphere in the closest compartments to the broken fan, as well as a lingering odor of sweat and engine grease.
3. Animal Loose in the ducts
On their last planetary visit the crew picked up an unwanted passenger in the form of some furry creature, (better hope it's not a alien variation on the skunk) that's making a home for itself in the ducts. (Or perhaps the escaped pet of a passenger or former owner of the ship)
Until it's removed the constant skittering of the animal will likely prove distracting to those trying to sleep or concentrate, and it may chew into insulation and/or wiring to make a nest for itself, (Could be it's pregnant as well?) causing all sorts of nasty side effects. If not dealt with in a timely fashion it may also die and give the surrounding compartments the lingering (possibly overpowering) odor of a decaying body.
4. Something's Gumming up the Plumbing
A clogged coolant pipe, broken coolant pump, or malfunctioning heating coil is causing the sudden overheating or freezing of ship components. Until it's fixed the adjacent compartment is going to be several (or more) degrees hotter/colder then desired and could also lead to the problem below.
5. A Soggy Situation
Perhaps caused by the previous problem, weapon/asteroid impact, or a high g maneuver/rough landing, an old weld on a water or sewage pipe has cracked loose; causing one of the pipes to leak or gush forth its contents rapidly. (Better hope the auto shut off valve is functioning properly!)
In the short term this could prove a minor nuisance. From, water damage to ceiling tiles, shorting out lighting fixtures, or even flooding a crew compartment entirely. If it's sewage line, the unbearable stench throughout a portion of the ship could make for plenty of problems on its own.)
The long term effects can range from an outbreak of legionnaires disease, fungus eating away at insulation, the rusting of other ship components, to perhaps the even more deadly problem of the majority of the ships drinking water having just become contaminated/unrecoverable.
If the ship is more then a couple days from a convenient place to replenish their water supply things could quickly turn ugly, especially if one or more of the crew or passengers become convinced the remaining water rations will go farther if there's less mouths to drink it up.
6. You Dropped it Where?
Perhaps it's a passengers wedding ring, or the key to the armory, but it's fallen through the grating/into a vent and needs to be recovered asap. (If it happens during a turbulent landing then the item could have bounced and slid a fair ways from its original drop point.)
If combined with the animal from complication #3, (which just happens to like shiny objects) finding the item again may well take some time and effort. (Better pray those pirates don't breach the airlock before the armory key is recovered eh?)
7. Treasure hunt!
Perfect for a newly acquired ship or one with a long history; either way the crew hears a rumor the former owner/s hid a small "rainy day" safe of valuables in the ducts for use in an emergency. (Whether or not the rumor holds true or the safe contains many valuables at all, the crew is likely to poke into every crawl space crevice in search of it.)
8. Micro Hull Breach
While barely large enough to be noticeable, this small hull breach is causing a slow depressurization of the air duct and adjoining compartments. If not patched, the ships store of breathable atmosphere will eventually run out after several weeks or months.
After a battle or meteor storm dozens of these hull breeches may be prevalent in duct work running near the ships hull. (This can also be a good cause for sections of a derelict being without atmosphere despite minimal surface damage.)
9. Rattle & Clank
A nuisance more then immediate hazard, this odd rattle can be heard from various corridors and compartments echoing faintly from within the air ducts.
Noisy enough to make sleep in a quiet room difficult, and a constant distraction for those on watch, this random sound will quickly get on the crews nerves until someone delves into the ducts and locates the problem. (Likely nothing more then a loose pipe fixture or fan bolt)
10. Where There's Smoke…
A thin trail of foul smelling, smoke is trickling from the air or maintenance ducts. The source of the offending fumes could be caused by smoldering insulation, a seized fan, someone sneaking a stogie in the supply room, or the cook burning dinner in the galley. (again!) Regardless, a quick check in the ventilation system may be in order to ensure the smoke isn’t the first sign of a serious mechanical failure.
11. Lights Out
Some type of power surge keeps randomly blowing out the lights in the latrine, and according to the diagnostic it's a faulty power junction. Better hurry up, crawl around in the ducts and do a quick fix before the captain has to wipe up in the dark for a second time. On the bright side this job isn't all bad, after all those ducts *do* run over the top of the showers…
12. A Taste to Remember
Yet again those pesky food dispensers are only producing liver flavored drinks for any beverage other then water. One of the micro processors is in need of replacement before breakfast, or the morning tea & coffee will prove devastating to morale.
13. Gravitational Turbulence
Gravity on the bridge is perhaps unusually heavy, missing entirely, or even fluctuating dangerously. Tracking down and repairing this problem will probably get top priority, although fixing the issue in zero gravity could prove a bit tricky.
Some enterprising crew member or passenger, (perhaps a long time ago) set up a mini alcohol still in one of the little used maintenance crawl ways. An instant source of profit and illicit fun for those who make the discovery, constantly accessing the crawl way is sure to draw suspicion among the more watchful crew members, and the still itself an obvious explosive danger to the ship.
15. A Bug Hunt
Whether caused by a moldy sandwich dropped down an air shaft, a grain spillage in the cargo hold that dumped several pounds of grain through a floor grate, or the garbage disposal tube rupturing; a small infestation of annoying buzzing insects have taken up residence in the air vents.
Besides working their way into most compartments of the ship and being a nuisance to the entire crew, these insects have also begun to clog filters, and perhaps harvest insulation for nesting material.
16. Filter Maintenance
While admittedly a low priority on most vessels, the filters do need to be changed, especially those on fans and within air vents surrounding the kitchen.
Usually boring make work assigned to those who need to be kept busy, more then one sneaky crew member has been known to hide contraband behind a filter.
17. Love Nest
In a semi spacious intersection of the air vents a couple of the more amorous crew members (past or present) have deposited a ragged sleeping bag and a couple of pillows. This secret make out spot is sure to be of interest to any who discover it, and perfect blackmail material if they can find the habitual users.
Depending on it's proximity to regularly inhabited compartments however, the noise and/or unusual odors carried on the breeze during use may lead towards a perceptive crew member noticing something is amiss.
18. Hook Me Up
One of the recently refurbished crew quarters is in need of some entertainment upgrades. Time to run a few cables and patch them into the ships entertainment feed. (While they're running cable it'd be pretty easy to place a few micro cameras in the grates overlooking other crew quarters, and the showers if they had a mind to)
19. You Can’t Stop The Signal
What ship wouldn’t benefit from a communication system upgrade? Unfortunately a higher end com array often requires a circuit and cable upgrade to go with it. However opportunity to splice in a few extra wires for a private communication channel and to eves drop on any message sent or received by the ship, may prove too tempting for most.
20. Crowd Control
Perhaps the best non lethal way of suppressing mutiny and passenger riots is with a discreet knock out gas dispersal method. Installing these mini canisters in key air vents along with the remote control system in a way that won’t be seen during normal maintenance is a delicate, yet important task best left to the most trusted of crew members.
21. Writing On The Wall
Part of what looks like the coordinates to an unknown location is found carved on the inside of an air grate. If checked, other grates holding more of this puzzle can be found around the ship and further inside the air ducts. Whether the coordinates are a red herring, or lead to lost treasure will never be known unless all of the numbers can be found.
22. The Haunting of Maintenance Duct #13
A run down and oddly colder then usual maintenance duct, #13 is little used, running under the primary waste recyclers. Spacer legend tells that every room and corridor numbered thirteen harbors the lost spirits of the men and women who have died on the unfortunate vessel during its journeys.
This duct however seems to be the proof behind the tale, with strange apparitions and haunting noises reported by all who are unfortunate enough to be tasked with working there.
Whether caused by hallucinations from toxic fumes leaking from the waste recyclers, a real life haunting, or some pranksters holo emitter this duct is loathed by everyone who's been forced to endure it's cramped confines for more then a few minutes.
23. Duct, Duct Goose?
A product of bored maintenance crews more then anything else, this game is a variation of the kids game by a similar name. Rather then having the "goose" chase the person who is "it" around a circle of their piers, this versions involves a mad dash by the "goose" through the ducts to find and tag whoever is "it" before they reach a designated safe zone. (Other variants include one or both players having to drink a specified amount of hard liquors before beginning.)
While disruptive, somewhat dangerous, and likely to cause minor collateral damage to hardware within the ducts and vents, the game does help mechanics quickly learn the interior layout of a ship in record time.
24. Silence Please
Noise, either from the engine room, a cargo hold of terrified cattle, or the newlyweds down the hall, has made soundproofing of one or more areas a necessity.
Refurbishing vent walls with sound absorption paneling can prove a time consuming task, especially if easy access to critical components needs to still be possible.
Installing a new ladder in one of the vertical shafts sounds like an easy, if boring task to occupy an afternoon. Of course the array of pipes and wires that lurk right behind the rungs can make securing them a tricky situation where a single mistake could cause a multitude of other problems.
26. Give Me What I Want or Else!
One of the passengers has suffered some kind of mental breakdown, perhaps from drug withdrawal, or bearing witness to an atrocity onboard the ship. Now they have barricaded themselves within a section of the maintenance crawl ways and are holding a vital piece of the ship hostage.
Unless the crew can successfully negotiate with this deranged lunatic and meet their bizarre demands or disabled them entirely, something will be going terribly wrong very soon. From the toilets all back flushing into to the galley, to the primary hydraulic lines being severed, the resulting situation will be both costly and damaging.
27. Tight Fit
One of the more "robust" (as in morbidly obese) passengers attempted to hide their contraband from the next port inspection, within the air ducts. Unfortunately, due to their girth they’ve become rather firmly lodged within the vent itself.
While amusing at first, this situation has the potential to become smelly and disruptive in a hurry. Especially if the crew is slow to discover their heavy weight passenger is missing. (which will probably be when the crew notices they missed the dinner bell.)
One or more of the underage passengers have managed to gain access to the ships crawl ways and now have come up missing. Finding and returning them safely before their rich and influential parents discover they’re missing is all but critical to preserve the ship and crews reputation.
Perhaps the humidity control is malfunctioning, or the newly installed greenhouse isn't properly calibrated; whatever the reason condensation build up is becoming a problem within the ducts.
Likely to go unnoticed for some time, this will make the next maintenance job much harder due to the slippery surfaces and continual dripping. In some of the deeper parts of the system an actual fog or mist may be present, making visibility (and thus work) far more difficult.
30. Worn Out Insulation
Possibly from all the crawling about dealing with the previously listed problems, or just old age, some of the insulation lining a few of the ducts closest to the outer hull is wearing thin, requiring it to be cut apart, hauled out and replaced.
Until it's fixed a few compartments are going be hotter/colder then normal and some of the ships electronics/mechanics may ice up or overheat and fail.