DXB

As a new owner, I finally got to move into a T hangar that was quite a bit larger than my diminutive short body Mooney. The previous occupant of that hangar was a Piper Cheyenne, which fit with ease. However, the hangar turned out not to be infinitely vast - I trashed my left elevator the first time I pushed my plane back into it. Remember kids - The flight isn't over until the plane is fully secured in the hangar. You really should be able to log hangar entry and egress as PIC time.

Cheap fast good. One only occasionally encounters anecdotal evidence of this elegant mythical beast in the aviation world. By contrast, there are plenty of ham-handed Sasquatch-like shops out there.

I tend to file the full route to destination and then tend to cancel, or not, once I'm out of the SFRA, depending on circumstances and mood. I've never tried filing IFR to a fix. To be honest, I only do 3-4 departures per year out of the SFRA, usually from KGAI. I think the folks based inside the SFRA get equally comfortable with any flavor of departure. For me, it's easier to just file IFR than refer back to that kneeboard reference.

Ah, that flying b*tt pl*g rears its ugly head again. Kinda the anti-Mooney. I dismiss it solely on aesthetic grounds .

I fly in this area all the time. Whether you go VFR or IFR, they'll put you at whatever altitude they want you at in the NYC and Philly class Bs - in my experience it's not that different on VFR flight following vs. IFR. If you want max discretion, go VFR and stay clear of Bravo airspace until you get near Baltimore / SFRA. Flying in the SFRA is no big deal when VFR. All else being equal, I tend to enter and exit the SFRA IFR just 'cause I'm lazy -I don't want to waste mental energy thinking about SFRA flight plan entering through Wooly gate blah blah blah....

A request: Please post the number of accidents that had fatalities so far this year? I started a thread a while back after tabulating the # lethal accidents annually across the fleet annually since 1961. For the past decade, it was pretty stable at ~7/year when averaged over 5 year increments. Presumably the gradual decrease in size of fleet and hours flown over that period is continuing, so a big spike now would be particularly alarming.

A loud noise triggers a reflex that contracts the tensor tympani muscle, which pulls the ear bone attached to the eardrum (the malleus) inward into the middle ear space, thus tensioning it against the eardrum and thus stabilizing it from large amplitude movements that could damage the inner ear. A similar reflex contracts a second tiny muscle, the stapedius, which attaches to the stapes. The stapes is the last of the 3 little ear bones that connects the eardrum to the inner ear (specifically the cochlea) and makes direct contact with the cochlea via the oval window. The stapedius muscle thus directly prevents the stapes from banging too hard against the oval window of the cochlea, and the tensor tympani does so indirectly. The cochlea contains all those delicate hair cells that get damaged easily from either physical or chemical toxic insults, making us lose our hearing. The fact that these muscle protective mechanisms are evolutionarily conserved across mammals tells us how vulnerable the inner ear really is to loud sound. One can certainly feel some ear pressure from these muscles contracting in response to loud sound. There are also rhythmic spasms that some people can experience for these muscles even in absence of a sound stimulus that can be annoying. I'm not sure these reflexes have anything to do with the "ear suck" and some other types of dysphoria a subset of people experience with ANR - I tend to think not. I suspect those are phantom sensations that arise from aberrant sound processing within the neural circuitry of the auditory cortex of the brain. ANR forces the brain to process a strange new sound profile where the low frequencies just drop out asymmetrically. The central auditory system isn't adapted to process this kind of profile because it looks nothing like sound profiles encountered in the real world, and so the output the auditory cortex gives to your higher brain centers contains some aberrant signals. That's pure conjecture on my part, but there's surprisingly little that's known about the phenomenon it seems. I bet real hearing scientists who study the auditory cortex would have a lot to say about it. I'm not one of them though.

There are definitely times when I've stopped monitoring 121.5 in flight due to these distractions. Since 121.5 serves multiple serious functions and is also monitored by ATC, the constant meowing, LGB, etc. must annoy ATC as much as it annoys me. It probably also interferes with them using it to raise an aircraft on 121.5 from time to time. I gather there is also no recourse if some anonymous person were to abuse another ATC frequency either? If so, it seems strange that rarely happens.

That's actually my point - an ANR headset like your Telex 50D can afford to be comfortable by reducing clamping pressure (without ANR, an over the ear headset has to either be uncomfortably tight or bad at attenuation) - and the set you describe is only 4 oz heavier than a Bose A20 and 2 oz heavier than a lightspeed zulu.

A few misconceptions here.... "If your primary desire is hearing protection don’t get a Bose headset, or any other headset that doesn’t work well with the ANR off, reason is they are very poor passive sets, they rely heavily on the magic of ANR and that’s a great marketing tool. Salesman says just turn it on and see how good it is. Impressive isn’t it?" Don't use it as a passive set. A20s are inferior passive sets because the clamping pressure was reduced relative to over the ear passive sets in order to increase user comfort. Even with the reduced pressure, they provide objectively far superior noise attenuation in the frequency range where there's loud noise in our piston single cockpits. The fact that it facilitates cute salesman tricks is just a side benefit. "Problem is ANR can’t cover all freqs." True but it doesn't need to. The sound profile in our particular cockpits (i.e. turbines = different animal) is heavily biased toward the low frequencies where ANR excels, so it's not a problem. "So if you have a Bose or similar headset, wear the foam plugs under them and turn up the volume. The cheap foamies are actually extremely protective." Foamies are superior to ANR at the high frequencies, but that's not where the dangerous noise is in our cockpits, so the plugs aren't buying you much. The modest passive attenuation of good ANR headsets at high frequencies is more than sufficient for the low levels of sound present in the range of speech and higher. So all the plugs will do for you is force you to turn up the volume so you can hear ATC. Zero sum game at best. "Another way is to get a very good passive headset and add ANR to them, that gives you the best of both worlds, ANR on top of a good passive set really reduces noise." Again, an over the ear headset designed for optimal passive attenuation has a high clamping pressure. In principle, adding ANR to it may give the maximum low to mid frequency attenuation attainable, though foamies remain the gold standard for high frequency. But the added discomfort to the wearer doesn't seem worth it when ANR is so effective already within the sound profile of piston single cockpit noise. In the end there is no single optimal hearing protection strategy - each sound profile brings its own challenges. I'm just addressing the Mooney cockpit here.

That plane looks sweet. Price is high by conventional standards, but who knows in the bonkers current market - it may very well get full price. You can start there and work the price down depending what prebuy turns up. As always, start the inspect with the major deal killers - spar corrosion, steel frame corrosion, copious metal in suction screen and/or filter, evidence of undocumented and/or poorly repaired damage. If you get it, be of a mindset to shell out for an overhaul in the not too distant future - who knows when the time will actually come. And hurry up and finish your PPL so your new Mooney doesn't sit around and rot ! You could train in it also, but that will slow down your license considerably and also require you to find a Mooney-specific CFI who is willing to take you on for primary training.

Yup - I should have added any significant change from baseline (even at "safe" levels) for a given flight condition should warrant close inspection of the entire exhaust, not just the muffler. Also @PT20J makes an important point regarding much more CO at rich mixtures. The graph below is the best I could find to illustrate. Mixture changes obviously have a big impact while ROP, so it's not alarming for the baseline to be higher at takeoff and after GUMPS. Below a stoichiometric mixture, the curve flattens out significantly, but there are still potentially threatening levels of CO produced at even the leanest combustible mixture, so being deep LOP does not assure safety.

Getting back to the original question here before this thread had to shift to correcting misunderstandings of cardiopulmonary physiology. 10ppm in flight in and of itself should be no big deal, though admittedly its impact on hemoglobin oxygen delivery to tissue would increase as altitude goes up in a way that the OSHA standard levels don't fully capture. I originally didn't want a Sensorcon specifically because I didn't want to know about levels that low getting into the cockpit in flight - it provides a meaningless number as a source of stress without detecting real hazard. One could reasonably look for small gaps in the firewall and cabin floor that could be sealed easily based on that information, but those gaps aren't ever likely to become really dangerous. I've changed my opinion a bit after the experience of @AlexLev. He saw very low levels in the cockpit with the heat on, but his baseline with heat off was zero in flight. I told him to blow it off (pun intended?). Investigating further led to him finding a minute hole in his muffler leaking into the heat shroud - that tiny hole could have grown rapidly to become seriously life threatening in a hurry on a cold winter flight. It was a good early catch that was facilitated by the high sensitivity of the Sensorcon. I think the bottom line is that low levels are acceptable in cruise and perhaps inevitable on the ground. However, any increase upon turning on the heat warrants close inspection of the muffler.

This may address @midlifeflyer 's question... I wondered why the superior comfort and high frequency deadening of foam ear canal insert-based headsets haven't been effectively combined with the superior low frequency performance of ANR. I think part of the answer is that effective ANR for low frequency relies in large part on a microphone inside the ear cup to drive the cancelling wave generation algorithm. The insert-based headsets may not have room for such a microphone. There is this Bose earbud-based headset and a couple cheap knockoffs on the market that I suspect use an external microphone to drive ANR, but their performance does not seem suitable for the low frequency-biased noise profiles of our planes. They are marketed for jets exclusively, and I wonder if they're really any better than foam inserts in that environment. https://www.bose.com/en_us/products/headphones/aviation_headsets/proflight-aviation-headset-ii.html#v=proflight_hdst_ii_portable

Yeah I've noticed mine performs much better on LPV approaches in GPSS/HDG mode than ILS in Hi-Trk mode, which is kinda unfortunate.

I'm actually not sure what's back there. The mounting screw was actually pretty long because there is a gap between my panel and the hole for the screw. Once I got a screwdriver to touch the base of that hole, a 180 degree turn toward the course was enough to take away most of my 1500 ft offset. Then it took a bunch of trial and error with small turns in both directions before I figured out how precise it could get. I did the whole thing in GPSS while on a victor airway with the default nav page of my GTN650 measuring crosstrack in real time. I used a 1/32" screwdriver from a cheap set of jeweler screwdrivers like the one below. The black business end of the driver isn't nearly long enough, but the handle is so skinny that it fit into the screw hole in my panel and the one beyond it on the STEC30. I'm not sure a driver with even a slightly fatter handle would have worked. It took some trial and error feeling for the screw hole in the STEC30 head before I got the driver tip in the right place to work. https://www.ebay.com/itm/332853777963?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=332853777963&targetid=1262779892849&device=c&mktype=pla&googleloc=9010328&poi=&campaignid=10459841973&mkgroupid=123050527180&rlsatarget=pla-1262779892849&abcId=2146002&merchantid=116333718&gclid=Cj0KCQjw8p2MBhCiARIsADDUFVF6sDZ7-O_SKSIec3X895TTWaMS0ulyxUYpUEFNXS_jI6i-WjgsQYQaAqCSEALw_wcB BTW I did this over rural North Carolina in smooth air with no airspace or traffic nearby and a quiet radio. Still, the attention required did lead to some loss of situational awareness.

Agree oil on the nose wheel after it sits post flying is NEVER normal and worthy of immediate attention. Some good possible sources are mentioned above. In my case it was a loose mag. If you can’t find the issue clearly, then clean everything up really well, add a little uv dye to the oil, run up on the ground, look with UV flashlight carefully. Still don’t see it? Fly exactly one lap in the pattern (the oil blows everywhere so a prolonged flight will make it hard to find). Look again with UV flashlight. BTW there is not a good approved low cost dye choice I don’t think, but adding a little of this stuff is pretty safe in my estimate. The oil itself has a bit of fluorescent dye in it already so it might work even without adding something. https://www.toolsource.com/leak-detectors-c-1321_1_4/mini-12-led-true-uv-flashlight-and-dye-kit-p-150875.html https://www.amazon.com/ACDelco-10-5045-Multi-Purpose-Fluorescent-Detection/dp/B008I2VPC4/ref=asc_df_B008I2VPC4/?tag=hyprod-20&linkCode=df0&hvadid=312061979255&hvpos=&hvnetw=g&hvrand=7587869341174403223&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9010328&hvtargid=pla-570750857018&psc=1 https://www.harborfreight.com/uv-blacklight-flashlight-63931.html?ccdenc=eyJjb2RlIjoiOTQ2NTQxNTciLCJza3UiOiI2MzkzMSIsImlzIjoiNi43NDI1In0%3D&utm_source=google&utm_medium=cpc&utm_campaign=15142691993&campaignid=15142691993&utm_content=127879545743&adsetid=127879545743&product=63931&store=223&gclid=Cj0KCQjw8p2MBhCiARIsADDUFVESIAqm-wEAIPLVjAww_sinrGIH150QK5Q5w1LCtt8VdT0mRQee58EaAkUAEALw_wcB

Did this adjustment in flight this eve - definitely a win. I did it in calm air at 8000 ft in GPSS MODE. My cross-track error went from 1500 feet right of course to pretty much right on (oscillates 200-400 feet to either side). That’s as good as I could get it though. @Jim Peace’s 500ft error might not be that far off from what’s possible. I thought it might do a better job flying an ILS so I gave it a try - nope - it still acted like a drunken sailor down the localizer course. Oh well, I’m still gonna call it a win

For part 91, just IRAN it via a good shop, not overhaul. Cheaper, fixes everything you need and nothing you don’t. Overhaul means grinding the blades and if they end up thinner than spec (real risk, particularly if overhauled before) then you pay $$ only to trash the prop in the end. BTW a small amount of grease seepage past the seals is not a big deal. Usually its Aeroshell #6 grease, which likes to break down and liquify. If it’s minor, you can just keep an eye on it in this state for a very long time, top it off periodically with a couple squirts of #5 into the hub. If you get it IRAN’d the seals will get addressed. If the prop was IRAN’d or overhauled shortly before going on your plane 2 years ago, it’s probably best just to watch it. But with the AD hub, I’d be inclined to get rid of that painful AD if the prop is gonna come off the plane for service. In that case a different prop altogether may prove the most economical path.

Bastard offspring from an affair between an M22 and an Aerostar F model??

dB is indeed dimensionless so the label is a bit nonsensical, but I think dB can be expressed as a ratio of power levels or of SPLs. I think the 130 dB pain threshold is derived from a power level ratio? There does seem to be some variation in how dB is used across human hearing study vs. acoustics, and my understanding of the differences gets fuzzy here. But on an audiogram, dB is expressed as HL (hearing level), which includes a correction factor at each pure tone frequency to reflect the lack of uniformity in the human detection thresholds across the frequency spectrum. So when I see dB SPL instead of HL, I just assume they are expressing dB without the correction factor - I could be wrong on that. Regarding the tensor tympani and stapedius reflexes (which stabilize the tympanic membrane, not constrict the eustachian tube), that was my hypothesis as well (see point 5 in my discussion above). On further reading, it seems more likely to be some kind of phantom sensation arising from aberrant central processing of sound that only affects some people (links above), but it's poorly understood.

Some ANR-related phenomena that may be similar to what you and @Hank describe: https://www.nytimes.com/wirecutter/blog/how-do-noise-cancelling-headphones-work/ https://www.soundstagesolo.com/index.php/features/178-eardrum-suck-the-mystery-solved These types of issues are clearly real, though I can find zero scientific literature on it. I can't imagine how it would be dangerous, but I'm kinda fascinated. These sensations are indeed experienced by a minority of people with ANR. The problems sound like a poorly understood quirk of central auditory processing that happens when ANR suppresses noise in a certain portion of the frequency spectrum. I'll ask a real hearing scientist and report back at some point. I hope I don't have the issue, or I'll be putting the A20s I just ordered up for sale on here shortly .

Responding to issues raised by multiple folks below... (1) @jaylw314 “I was surprised at the claim that low frequency sounds might be more dangerous to hearing loss” Apologies if I gave this false impression. My claim is merely that low frequency sounds (<1000 Hz) are encountered at dangerous levels in Mooney cockpits to a far greater degree than higher frequency ones. (2) @jaylw314 Odd labeling of y axis units on Cessna flyer chart. I think the correct y-axis is simply decibels here. The 1.0W/m label should be 1.0W/m^2 (sound intensity), which equals 130db on the scale. Db is a weird scale calculated as db = 10 • log( I / 1.0 x 10^-12 W/m^2 ). It is designed to span the normal human hearing range of 0 db (threshold of detection) to 130 db (threshold of pain). (3) @jaylw314 Disparity between multiple cockpit noise profiles and paucity of data. Interpretation of the Cessna one I posted seems nearly identical to your Comanche profile, so that should provide some confidence that the most dangerous noise is really low frequency in our planes (reposted for comparison below). They look different because a smoothing function has been applied to the former, and the y-axis scale starts at 60db. Most of the damaging exposure happens above 60db, so the Cessna profile is still a reasonable depiction. I agree it would be helpful to have more data, and the optimal sound protection will be somewhat aircraft specific. E.g. the typical ANR profile may not be optimal for the sound profile of a whiny Rotax engine or a nagging spouse, and turbines seem a different sound animal altogether. But I don’t think it’s too far an extrapolation to suspect that Mooney cockpit noise profile is pretty similar to these two plots. (4) @jaylw314 What noise exposure level is damaging? 85 db as a time weighted average over 8 hours is indeed the widely cited OSHA standard for occupational exposure. This standard does not address hazards of potentially much louder sounds over shorter durations, which is what happens in our cockpit environments, or the consequences of less exposure to people with particular susceptibility (discussed below). It’s worth emphasizing that db is a log scale, so a 115db low frequency noise in the cockpit contains 1000-fold (!) the sound energy of the 85db sound. (5) @jaylw314 Is noise exposure even the dominant factor in hearing loss or is it primarily other factors as we age? It’s complicated. A few background facts: 1. Hearing loss with aging (presbycusis) isn’t inevitable – there are many elderly folks with near normal hearing. 2. Everyone is susceptible to noise induced hearing loss with high level prolonged exposure – the severe consequences from military and industrial environments are well documented. 3. The inner ear damage that causes hearing loss (loss of cochlear hair cells) is a threshold phenomenon – i.e. you can lose a lot of hair cell function as a young person without acquiring a measurable hearing deficit. But once you reach the threshold where it’s measurable, your reserve has been depleted, and effects of any further hair cell loss on hearing are perceptible. 4. There is a large genetic component that governs susceptibility to hair cell loss that is poorly understood, and this is a very active research area where new insights are expected in the coming years. 5. Drugs and other diseases certainly contribute to hair cell damage – e.g. certain chemotherapy drugs, Lasix taken by people with heart disease, the small vessel ischemia in the population with cardiac disease, high dose aspirin, even prolonged continuous use of ibuprofen/naproxen. Despite multiple complex interacting factors, I think the bottom line here is that those of us with significant tinnitus and any of the high frequency loss that it usually indicates have legitimate reason to be worried about further damage of any cause. (5) @Hank @Schllc Uncomfortable sensations upon turning on ANR. Other folks do describe something like this. As @EricJ says, it can’t be real pressure – All the ANR is doing is creating an absence of sound – kinda the opposite phenomenon. Extreme quiet from an ANR headset can be uncomfortable to people with sensorineural hearing loss due to worsened tinnitus, but that shouldn’t cause a pressure feeling. Loud sound triggers a protective muscle reflex designed to stiffen the eardrum in order to reduce sound reaching the inner ear (stapedius/tensor tympani reflex), so turning off that reflex by turning on ANR in a noisy environment might also create a perceptible ear sensation initially. Bottom line is I’m really not sure on this one and would like to learn more. (6) @Hank Use of non-foam earplugs (e.g. silicone inserts). Unfortunately, for ear canal inserts, foam plugs are the gold standard for sound deadening (28-33 noise reduction rating) and are measurably superior to silicone or wax (22-23 dB rating) or even custom molds. Dr. Phil correctly says as much on his website in favoring use of the foam inserts that come with the QTs.

I'd be curious to hear what Dr. Phil McCandless actually has to say on this topic - I don't see any published public claim by him that modern ANR technology is damaging to hearing, and so I won't personally attribute it to him at this point. But with caveats I posted above, any such claim would seem extremely hard to defend from first principles, at least for cockpit use. I also looked and don't see any scientific literature to substantiate the claim. Hearing protection is a heavily funded and studied topic in the occupational health realm, and so I'd expect far more research activity on this question even if harm from ANR was merely a plausible but unproven hypothesis. FWIW, I am a boarded otolaryngologist, saw hearing loss patients in a former life, and continue to serve as faculty in an academic department that contains multiple NIH-funded PhD hearing scientists - I'll run the ANR question by them at next opportunity and certainly report back if I've missed something. BTW I did look up Dr. McCandless' product website and found what seems like a misleading claim: "Properly inserted, the HALO(tm) is able to quiet the ENTIRE audio spectrum, not just the low frequencies of traditional ANR systems." Foam plugs attenuate roughly as well as passive over-ear protection in the low frequency range where most cockpit noise occurs; ANR is superior in that range by a wide margin. The foam plugs may be superior in the high frequencies, but there's just not much high frequency noise in our piston single cockpits. So the company trademarked slogan "Quiet as ANR - comfortable like nothing else" doesn't really apply to the cockpit sound environment where we are using it. To be clear - I think Halos are a great product - at least as effective as passive over the ear protection, far more comfortable than any over the ear headset, durable, and very economical - a great value overall. I only bought the more expensive Clarity Alofts originally because the Halos were on extended backorder. BUT, if optimal speech intelligibility and particularly long term hearing protection are the priority, then many of us may consider giving up the extra comfort for ANR.

I have two CiES senders in my C with 27.4 gallon/side bladders. You need 2 senders.