Jump to content

iChris

VR Member
  • Content Count

    1,010
  • Joined

  • Last visited

  • Days Won

    52

iChris last won the day on April 27

iChris had the most liked content!

Community Reputation

500 Excellent

About iChris

  • Rank
    VR Veteran Poster

Profile Information

  • Gender
    Male
  • Location
    California

Recent Profile Visitors

1,212 profile views
  1. The text you quoted states that "cruise-charts are not drag-charts, it can be noted the lowest point of a drag chart does not necessarily match the lowest point of the power required curve in a cruise chart." As in Eric Hunt's post above, D = P/V. Were P = rotor power (induced, profile) + the rest of the helicopter (parasitic, tail rotor). Eric already answered your question as to why. It's in the math, rearranging the equation D x V = P. It's a helicopter, not just D = P. You have to account for the V and the other power requirements. We're dealing with the total power required supporting more than just the drag of the helicopter. The issue is forward flight (cruising flight) performance. Another power drain is that the turbine engine is more efficient at high power than at low power because of the fuel-flow needed to keep the gas generator spinning, regardless of the power output. Fuel-flow is the center of interest. Remember, fuel-flow is proportional to power; that's why fuel-flow versus airspeed curves mimic the power-required curves. Power is proportional to Fuel-flow. To maximize endurance, we want to maximize the amount of time that we can stay in the air. Since the fuel flow is proportional to the power-required, fuel flows lowest when the power-required is a minimum. The speed corresponding to the bottom of the power-required curve is the speed for maximum endurance. To maximize the range, we want to get the maximum distance for each pound of fuel burned. Therefore, the maximum range airspeed occurs where a line from the origin is tangent to the power required curve or fuel-flow versus airspeed curve below.
  2. Refer to the specific series noncommercial/military flight manual. Maybe informational status only indication. Example Army OH-6A manual section below, even though calibration is also 35 pounds:
  3. In FAA’s eyes a "small rotorcraft:" 14 CFR Part 1.1 defines a small aircraft as an aircraft of 12,500 lbs. or less maximum certificated take-off weight. Therefore, any rotorcraft, could be considered small by the Part 1.1 definition (aircraft) if the rotorcraft/helicopter is less than 12,500 lbs. Part 1.1 Aircraft means a device that is used or intended to be used for flight in the air. Part 1.1 Small aircraft means aircraft of 12,500 pounds or less, maximum certificated takeoff weight. § 29.811 (f) Each emergency exit, and its means of opening, must be marked on the outside of the rotorcraft. In addition, the following apply: (1) There must be a 2-inch colored band outlining each passenger emergency exit, except small rotorcraft with a maximum weight of 12,500 pounds or less may have a 2-inch colored band outlining each exit release lever or device of passenger emergency exits which are normally used doors.
  4. Your speakers are not polarity sensitive so bands 2 & 4 (speaker wires) on the u174 may be reversed wired without a problem. The same for the mic bands 1 & 3 (mic). In most cases the mic is not polarity sensitive. However, with an older mic or special purpose designs, you may have to swap the mic wires around. Once you identify your mic wires, any reverse polarity won’t hurt the mic, it just won’t work, just swap it. Your PTT switch above is yellow/black wiring between your radio and the u94. It could be one or two wires. The one wire setup eliminates the extra wire run by using the shield ground at the u94, see photo below. What you have is a momentarily "on" switch that grounds the radio's PTT circuit to key the mic. If you’re going to eliminate the switch, you don’t need the yellow wire. If not, the yellow wire should go to one of the two terminals on the switch and the other switch terminal should have a connection to the black (GND) wire. On one of the four terminals on the u94 receptacle, you may find a black and white wire soldered to the same terminal. There’re using the black (GND) wire as the speaker return wire Isolate-Detect- Correct, the old troubleshooting adage.
  5. From your post, I assume you’re trying to replace the u-94 jack with a u-174 plug or trying to make an adapter cable with a u-174 at each end so as not, destroy the u-94 jack. With the documentation at the link below, you should be able the back-track the wiring. Open up the u-94 jack and plug in the u-174 plug. From there, you can back-track the known wiring form the u-174 back to the correct connections on the u-94 side. You can also see how the David Clark H10-76 u-174-plug wiring matches up with the u-94. It’s not as hard as it may seem, the system effectively (on the headset end) only uses four (4) wires, two (2) wires to the mic, two (2) wires for the speaker or earpiece. The only reason you have six (6), is they parallel-off two additional wires from the base pair of speaker wires to a second speaker or earpiece. There may be a seventh wire, often used as a shield ground. Upstream of the u-94, you normally have six (6) wires. Again, two wires for the speaker/earpieces and two for the mic. The remaining two wires for the Press-To-Talk (PTT). PTT wires are often blue/yellow, mic- red/white, speaker-white/black or white/green. The normally always wires are, red-mic and white or black speaker. Color codes may differ between manufacturers, so don't expect a color-color solution. However, plug and terminal designations are constant. See link: Wiring Document U94/U174 Your u-94 is probably pretty close to one of these below: u-94 color/function Red- Microphone High White- Microphone Low Green- Speaker High Black- Speaker Low Yellow - PTT High Blue- PTT Low
  6. It appears your memory hasn't failed you. At least that was the way it was before Airbus. Maybe the qualified flight instructor requirement part came in later manuals.
  7. The ability of the compressor to pump air is a function of RPM. At low RPMs, the compressor does not have the same ability to pump air as it does at higher RPMs. To keep the blade angle of attack and air velocity within desired limits and prevent compressor stall, it is necessary to "unload" the compressor in some manner. In other words, the compressor needs to see less restriction to the flow of air through the use of a compressor bleed air system. CLICK PHOTO TO ENLARGE
  8. You don’t need to rebuild the R22/R44 helicopter or overhaul its engine. However, regardless of the certificate, the aircraft has to be airworthy. It is well-established that an aircraft is deemed 'airworthy' only when it conforms to its type certificate (if and as that certificate has been modified by supplemental type certificates and by Airworthiness Directives), and is in condition for safe operation. Experimental won’t get you pass that. It's a documented practice in line with FAR 43.15c and Appendix D to Part 43. If the aircraft is not used for compensation or hire it could be operated part 91 under the annual inspection only requirements of 91.409a. In that case (with respect to the engine) there would be no required engine overhaul. You could continue on each year as long as the engine passes the annual inspection requirements in Appendix D to Part 43. That’s your on-condition operation. Also, as long as the owner complies with chapter 3 page 3.9 or page 3.10 in the R22 maintenance manual, the aircraft and engine can be maintained under FAR 91.409a, 43.15c, and Appendix D to Part 43 in an airworthy condition. To fully understand you may need to read the posts below and the supporting documentation. R22 Airworthiness past 2200hrs/12yrs R44 12-Year Inspection Required for Part 91? Legal Interpretation MacMillan Apr 22, 2011 FAA Order 8620.2B - Applicability and Enforcement of Manufacturer’s Data
  9. NTSB Updates on Kobe Bryant Accident A ground camera captured an image of the helicopter entering the clouds. Radar/ADS-B data indicate the aircraft was climbing southwesterly along a course aligned with Highway 101 just east of the Las Virgenes exit, between Las Virgenes and Lost Hills Road. The helicopter reached an altitude of 2,300 feet msl, approximately 1,500 feet above the highway, but below the surrounding terrain when it began a left turn. Eight seconds later, the aircraft began descending as the left turn continued. The descent rate increased to over 4,000 feet per minute while the ground speed reached 160 knots. The last ADS-B target was received at 1,200 feet msl approximately 400 feet southwest of the accident site. A still photo obtained from a security camera located in a road maintenance yard adjacent to Mureau Road and Highway 101 showed the helicopter proceeding westward along the highway and disappearing into the clouds. Mureau runs just to the north of Highway 101. The Board as yet does not know why the pilot entered the clouds. NWS photo looking east from a hill near the crash indicates the tops of the clouds near the site were about 2,400 msl. Full text: NTSB Updates on Kobe Bryant Accident By Rob Mark
  10. The quote was Aviation accidents.... Job-related mortality of wildlife workers in the United States, 1937-2000 “Abstract Wildlife biologists face a variety of job-related hazards that are unique to this profession, most of them involving the remote areas where work is performed and the unusual techniques used to study or manage wildlife. Information on biologists and others killed while conducting wildlife research or management was obtained from state and federal natural resources agencies, solicitations on wildlife-based internet discussion groups, and published obituaries. Ninety-one (91) job-related deaths were documented from 1937 to 2000. Aviation accidents, drowning, car and truck accidents, and murder were the most common causes of death. Thirty-nine (39) aviation accidents accounted for 66% of deaths, with aerodynamic stalls and power-line collisions being the most significant causes of accidents for which information was available. These safety threats should be taken into consideration during the design and planning of future research and management projects.” REF: https://www.jstor.org/stable/3784446?seq=1 Some communities have enacted zoning laws, building codes, fire regulations, etc. that can affect establishment of helicopter landings in residential neighborhoods. They’ve developed codes or ordinances regulating environmental issues such as noise and air pollution. A few localities have enacted specific rules governing the establishment of a heliport. Therefore, contact officials or agencies representing the local zoning board, the fire, police, or sheriff's department, City Council, and the Mayor’s office. Get with your neighbors, kill it at the local level, and the FAA will not approve it in opposition to local laws. Also: http://stophelipad.org/home.shtml
  11. That S-76B was operated single-pilot VFR, Part 135 charter, limit 9 PAX seats. That wasn’t an IFR operation. That’s also why neither Cockpit Voice Recorder (CVR) or Flight Data Recorder (FDR or Black Box) are required (135.151 or 135.152).
  12. The 90gal/hr is a bit high for single engine operation. However, that's in the range with both engines online, 0.5 - 0.6 (80 - 97 gal/hr ) in terms of efficiency, you're looking for < 0.7 SHP(takeoff) = 1100 (0.5 * SHP)/6.8 = 80gal/hr (0.6 * SHP)/6.8 = 97gal/hr
  13. There’s a typical 0.5 - 0.8 Ibs/hp/hr specific fuel consumption (SFC) index for modern turbine engines. Light helicopter turbines, 0.5 is a good average The Bell 429’s one engine inoperative (OEI) 30 minutes hp = 550 SHP. So your OEI would average around: 40gal/hr. @550 SHP (jetA est. 6.8lbs/gal)
  14. You take calculated risk every time you go and fly. It’s how you manage that risk, how you plan ahead for it, and deal with it that makes it dangerous or not dangerous. One thing is sure, dangerous or not, it’s unforgiving of poor decision-making
  15. Delorean’s post above gives an excellent description of the system. The system is fairly simple. You have a solid-state control unit mounted behind the left seat back. The controller senses engine RPM via tachometer points in the engine right magneto and provides a corrective signal to the governor assembly. The governor assembly gearmotor is attached to the collective stick assembly behind the left seat. When activated by the controller, the gearmotor make the required RPM adjustment by driving a clutch connected to the throttle. The following is a quote from the R22 maintenance manual: “The majority of governor problems are caused by the engine's right (helicopter left side) magneto tachometer contact assembly (points) being out of adjustment or faulty.” Garbage-in garbage-out, engine right magneto or wiring problems upstream of the controller can result in strange or intermittent issues. The controller may not be the problem. Check out the link below pages 8.34A RPM Governor System and 8.34C Governor Troubleshooting https://robinsonheli.com/wp-content/uploads/2018/11/r22_mm_8.pdf click photo to enlarge
×
×
  • Create New...