AC 43.13-1A Page 293 1972 Section 2. MAINTENANCE OF WIRING AND CABLES
766. WIRING AND CABLE INTEGRITY. Inspect interconnecting wiring, cables, and conduit betweer various pieces of electronic equipment to determine that they do not rub against the airframe or each other under vibration conditions encountered in flight. Inspect open wiring and cabling for fraying, damage or distortion resulting from heavy objects being placed on it, being stepped on, or being used as hand-
767. PROTECTION FROM FLUIDS. Separate wiring or cables for flammable fluids lines or those which carry fluids which have a deteriorating effect on wire insulation. Wiring or cables should be routed above such lines and securely clamped to the aircraft structure. An arcing fault between an electric cable and a fluid line may puncture the line and result in a fire.
768. WIRE AND CABLE CLAMPS. Inspect wire and cable clamps for proper tightness. Where cables pass through structure or bulkheads, inspect for proper clamping or grommets. Inspect for sufficient slack between the last clamp and the electronic equipment to prevent strain at the cable terminals and minimize adverse effects on shock mounted equipment.
769. CONDUIT, Conduit is manufactured in metallic and nonmetallic materials and in both rigid and flexible forms. Primarily its purpose is for mechanical protection of the cable within. Inspect conduit for proper end fittings, absence of abrasion at the end fittings, and proper clamping. Inspect for distortion, adequate drain points which are free of dirt, grease, or other obstructions, and freedom from abrasion or damage due to moving objects such as aircraft control cables or shifting cargo.
770. PLASTIC WIRE SLEEVING. Inspect plastic wire sleeving for damage due to abrasion, solvents, or hydraulic fluids.
771. ELECTRICAL TAPE. The chemical base of most plastic electrical tape is polyvinylchloride (PVC). This tape is not flame resistant unless it is specially processed to make it so. Some manufacturers are producing flame-resistant PVC tape and have obtained Fire Underwriter's Laboratory (UL) approval which is shown on the wrapping of the container. Unless the tape shows such approval, it should not be used until its flame resistance properties have been determined. A simple test can be made by applying a flame to a sample of unknown tape and comparing its burning qualities to a sample of flame-resistant tape.
Flame resistant or not, PVC will decompose at temperatures above 221° F. (105° C.) with rapid loss of insulating qualities. It is not recommended for use in compartments where temperatures normally approach 221° F. (105° C.)
nor in designated fire zones unless precautions are taken to prevent short circuits to the airframe, shielded wires in bundles, or any other electrical ground, in the event of decomposition.
772,-782. RESERVED.
Chap 15 Рат 766
Page 294 AC 43.13-1A 1972 Section 3. JUNCTION BOXES AND TERMINAL STRIPS
783. JUNCTION BOXES. Inspect junction boxes for "oil canning" of the cover and sides, internal shorts due to distortion of the box, internal cleanliness, absence of stray metallic objects, proper grommeting where wires or cables enter the box, and freedom of drain holes from foreign objects or material.
784. INTERNAL ARRANGEMENT. Dlectric cable inside the box should be laced or clamped in such a manner that terminals are not hidden, relay armatures are not fouled, and motion relative to any equipment is prevented. Where marginal clearances are unavoidable, an insulating material should be interposed between currentcarrying parts and any grounded surface.
785. TERMINAL STRIPS. Inspect terminal strips which provide connection of radio and electronic systems to the aircraft electrical system for loose connections, metallic objecta which may have fallen across the terminal strip, dirt and grease accumulation, etc. Such conditions can cause arcing which may result in a fire.
786. PLUGS AND RECEPTACLES. Inspect this type of power connector for loose soldered connections, proper insulation of metallic parts, and fraying of wires in the plug and receptacle inserts.
787.-797. RESERVED.
Par 783 Chap 15
AC 43.13-1A Pago 995 1972 Section 4. POWER SOURCES AND DISTRIBUTION SYSTEMS
798. BATTERY ELECTROLYTE CORROSION. Electrolyte spilled during ground servicing should be neutralized at once with solutions of sodium bicarbonate (for acid electrolyte) or boric acid, vinegar, or a 3 percent solution of acetic acid (for alkaline electrolyte). Residue should be washed off with clean water and the area thoroughly dried.
799. GENERATORS AND ALTERNATORS, Inspect generators and alternators and their associated wiring and distribution systems for wear, damage, general condition, and proper functioning to assure the continued satisfactory operation of the electrical aystem. Frequent visual inspections, operating checks of all electrical circuits and equipment, and replacement or repair when deficiencies are found are effective in minimizing electrical troubles and hazards in aircraft.
short circuit and will generally destroy them instantly.
802. ALTERNATOR/BATTERY CONNECTIONS. Some alternators require that the battery be connected in the circuit initially before it will produce any output.
803, STATIC ELECTRICAL POWER CONVERTERS.
Static power converters employ solid state devices to convert the aircraft primary electrical source voltage to higher values for the operation of radio and electronic equipment. They contain no moving parts and are relatively maintenance free. Various types are available for AC to DC or DC to AC conversion. Exercise care in locating and mounting static converters to insure adequate ventilation for cooling purposes. Heat radiating fins should be kept clean of dirt and other foreign matter which may impair their cooling properties.
800. ALTERNATOR DIODES. Alternators employ diodes for the purpose of converting the alternating current to direct current. These diodes are electronic devices and are particularly susceptible to damage if abused. A diode will allow passage of current in one direction with little resistance, but will allow passage of current in the opposite direction only if the voltage applied exceeds that value for which the device was designed. A voltage surge in the line, if it exceeds the design value, will destroy the diode very quickly.
801. DIODE PROTECTION. The best protection against diode destruction by voltage surges is to make certain that the battery is never disconnected for the aircraft electrical system when the alternator is in operation, The battery acts as a large capacitor and tends to damp out voltage surges. Make certain that the battery is never connected with reversed polarity. This will subject the diodes to a direct
804. CLEANING AND PRESERVATION. Frequent cleaning of electrical and electronic equipment to remove dust, dirt, and grime is recommended. Fine emery cloth may be used to clean terminals and mating surfaces if they appear corroded or dirty. Crocus cloth or very fine sandpaper should be used to polish commutators or slip rings. Use of emery cloth on commutators is not acceptable because metallic particles from the cloth may cause shorting and burning.
805. MISCELLANEOUS CHECK ITEMS. Make frequent checks for miscellaneous irregularities such as loose terminal connections, poorly soldered or loosely swaged terminals, missing safety wire, loose quick-disconnects, broken wire bundle lacing, broken or inadequate wire clamps, and insufficient clearance between exposed current-carrying parts and ground. Replacement or repair should be accomplished as & part of routine maintenance.
Chap 15 Par 798
806. ADJUSTMENT AND REPAIR, Accomplish all adjustment, repair, overhaul, and testing of electrical equipment and systems in accordance with the recommendations and procedures set forth in maintenance instructions or manuals published by the aircraft and equipment manufacturers.
807. ELECTRICAL SWITCH INSPECTION. Special attention should be given to electrical circuit switches, especially the spring-loaded type, during the course of normal airworthiness inspection. An internal failure in this type of switch may allow the switch to remain closed Par 806 AC 43.13-14 1972 even though the toggle or button returns to the "off" position. During inspection, attention should also be given to the possibility that improper switch substitution may have been
808. RADIO EQUIPMENT OPERATION. Determine that the radio and electronic equipment operates satisfactorily throughout the voltage range of the aircraft electrical system under taxi, takeoff, slow cruise, normal cruise, and landing operating conditions.
809.-819. RESERVED.
Chap 15
AC 43.13-1A Page 297 1972 Section 5. NOISE SUPPRESSION
820. GENERAL. Elimination or suppression of sources of radio interference within the aircraft is necessary in order to obtain the optimum performance of airborne radio equipment. This is done by bonding, shielding, and the use of static dischargers.
821. BONDING. Radio equipment should be bonded to the aircraft in order to provide a low impedance ground and to minimize radio interference from static electricity charges. Bonding jumpers should be as short as practicable and be installed in such a manner that the resistance of each connection does not exceed
0.008 ohm. Where a jumper is for radio-noise prevention only and not for current-carrying purposes, a resistance of 0.01 ohm is satisfac-
822. SHIELDING. The most effective method of minimizing engine ignition radio interference is to shield the ignition system. Use a metallic braid covering and special end connectors for ignition wires between the magneto and spark plugs. The primary leads to the magneto and the magneto switch itself should be shielded.
Provide shielded type spark plugs and a shielded metal cover for the magneto if it is not so equipped. All connections in the shielding should be tight metal-to-metal contact.
823, SPARK PLUGS, The engine ignition noise may be suppressed by replacing the spark plugs with resistor spark plugs of a type approved for the engine if it is not feasible to shield the engine ignition system.
824. FILTERS. If an intolerable radio noise level is present despite shielding of the ignition wiring and plugs, it may be necessary to provide a filter between the magneto and magneto switch to reduce the noise. This may consist of a single by-pass capacitor or a combination of capacitors and choke coils. When this is done, the shielding between the filter and magneto switch can usually be eliminated and the special shielded magneto switch need not be used.
Inspect supporting brackets and wiring details for magneto filters for conformance with standard aircraft electrical practice. The reliability of the magneto filter installation should be at least equivalent to that of the remainder of the magneto ground lead installation.
825. PRECIPITATION STATIC, Precipitation static is a general term applied to noise in radio receiving systems caused by precipitation. It is not always caused by true precipitation, such as ice, snow, or rain. Dust, sand, or other airborne particles may cause it. It may be the result of ionization in the exhaust of jet engines.
As a result of precipitation static charging, the electrical potential of the aircraft rises until it reaches the corona threshold. Corona is the discharge of electric current from an object into the surrounding air and occurs as short pulses of current and produces a noise spectrum which contains appreciable energy at radio frequencies. The noise produced is coupled into the aircraft antennas.
826. STATIC DISCHARGERS, Static dischargers are installed on aircrait to bleed off precipitation static before the potential reaches the corona threshold. These dischargers are normally mounted on the control surfaces and other extremities of the aircrait. The three major types in use are: (1) flexible, vinyl-covered, carbon-impregnated braid, (2) semiflexible metallic braid, and (8) null-field.
827, MAINTENANCE OF STATIC DISCHARGERS.
Inspect flexible and semiflexible dischargers for physical security of mounting attachments, wear or abrasion of wicks, missing wicks, etc.
Inspect flexible, vinyl-covered wicks to assure that one inch of the inner braid extends beyond Chap 13 Par 820
Page 298 AC 43.13-1А 1972 the vinyl covering. Null-field discharges are mended tolerances, and inspect for physical epoxy bonded to the aircraft structure. Meas- damage.
ure the resistance of the bond to determine compliance with the manufacturer's recom- 828.-838. RESERVED.
Par 827 Chap 15
AC 43.13-1A Page 299 1972 Section 6. ANTENNAS
839. FIXED AND TRAILING WIRE ANTENNAS. Inspect fixed and trailing wire antennas for cracked or broken insulators, broken tension springs, and missing end thimbles. Inspect feed-through and strain insulators for damage due to arcing or corona discharge. Replace damaged insulators. If insulated wire is used for the fixed antenna, inspect the insulating covering for pinholes resulting from corona discharge or lightning. Inspect fixed antenna masts for security of mounting and absence of skin cracks in the mounting area.
840. WHIP AND BLADE ANTENNAS. Inspect security of mounting, condition of sealant around antenna base, and physical damage resulting in bending or deformation of the antenna itself.
841. FLUSH MOUNTED ANTENNAS. Many high performance aircraft use flush mounted antennas where the antenna itself is recessed in the fuselage or other portions of the aircraft structure. The recesses in which such antennas are mounted are covered with fiberglass or other material which allows the passage of radio frequency energy. Inspect such covers frequently for integrity of seals and cracks in the covering. If the covers are painted, they should be painted with a type of paint which will not interfere with the passage of radio frequency en-
842. COAXIAL CABLES AND FITTINGS. Inspect coaxial cable antenna connectors for proper fastening. Certain types of connectors depend on the positioning of the center pin by its physical connection to the center conductor of the cable. Frequent connecting and disconnecting of the connector causes this pin to position so that it does not make contact with the female connector. If the connectors become physically separated from each other or the unit, equipment failure will result. Cable connectors may be clamped or safetied so that they do not become separated.
843. RADOMES. A radome is a covering whose primary purpose is to protect a radar antenna from the elements. It is a part of the airframe, but must have certain electrical as well as physical properties. Electrically, a radome must permit the passage of the radar transmitted signals and return echoes with minimum distortion and absorption. In order to do this it must have a certain electrical thickness. A variation in electrical thickness can make the difference between an efficient radome and one that can reduce radar range, distort displays, and cause inaccurate directions and false targets. Hence, a radome must be properly maintained and repaired to deliver optimum performance.
844. RADOME INSPECTION. Inspection of aircraft having. weather radar installations should include a visual check of the radome surface for signs of surface damage, holes, cracks, chipping, and peeling of paint, etc. Attach fittings and fastenings, neoprene erosion caps, and lightning strips, when installed, should also be inspected.
•. Scuft marks on the radome are usually ar indication of impact damage from birds, foreign objects, or hangar/ramp equipment. Further detailed inspection is required to determine whether physical damage has occurred.
b. Surface cracks on the radome paint do not always indicate structural damage, but may be due to paint shrinking or becoming brittle. If accompanied by impact marks, static discharge or lightning burn marks, or evidence of oil canning, a more detailed inspection is required to determine whether physical damage has oc-
Chap 15 Par 839
flight encounter with hail, surface static discharges, or lightning. A detailed external and internal inspection of the radome should be made for fractures or delamination of the radome structure.
d. Paint peeling on the radome is usually caused by flight in heavy precipitation or by improperly applied paint coatings. If detected in its early stages, usually no damage results.
Corrective action should be taken to prevent further erosion and water absorption. A rapid breakdown of the structure will occur when trapped moisture freezes resulting in greatly reduced efficiency of radar operation.
•. Neoprene erosion caps provide protection from rain erosion; however, they do conceal the radome surface and make impact damage difficult to detect. When in doubt about impact damage, remove the radome and inspect the inside surface. Other erosion cap inspection items are air bubbles, surface fraying, and loose edges around the cap.
f. Lightning diverter strips are intended to protect the radome from lightning damage, and prevent radio interference from static charge build-up on the radome. Proper grounding of these atrips to the aircraft structure should be assured each time a radome is inspected or repaired. Damaged or burned-out strips should be replaced.
845. RADOME MAINTENANCE AND REPAIR. Any repair to a weather radome should be accomplished according to manufacturer's recommended procedures by qualified personnel using the equipment and materials recommended by the manufacturer. The use of improper materials and repair techniques may result in reduced performance and accuracy of the weather radar system.
o. Plastic nose caps should not be installed over a radome unless the manufacturer recommends such installation. Such caps may cause radar beam distortion, weak signal returns, poor definition, and radar display clutter.
Moisture leaks or condensation between the plastic cap and radome can block or distort the signal without the cause for such condition being apparent.
Par 844 AC 43.13-TA 1972
b. Radome protective coating should be a type, and contain only materials, recommended by the radome manufacturer. Metallic paints or undercoating can set up reflections in the radar system which may damage the equipment.
c. Solvents should not be used to wash the radome. They may weaken the bond between the radome and the neoprene erosion cap.
d. Chemical type paint strippers should not be used. They will attack the resins used in the radome construction, and may weaken its structural integrity.
•. The testing of a radome after maintenance or repair is a determination that must be made by the person approving it for return to service since he is responsible for its airworthiness. All repairs to radomes are not necessarily major repairs, and minor repairs may not require testing. The decision to test should be based upon the nature and complexity of the
846. LOOP ANTENNAS. Loop antennas are designed for use with a particular receiver. Connecting wires between the loops and receivers are also designed for the specific equipment.
Use only components meeting the specification characteristics of the receiver manufacturer.
The outstanding characteristic of a loop antenna is its directional sensitivity which makes it useful as an accurate navigational device.
847. LOOP QUADRANTAL ERROR. Compensation of a loop for quadrantal error requires technical knowledge of the equipment and its operational use and should be accomplished only by a qualified technician. Quadrantal error is that error caused by the metal in the fuselage, wings, etc., distorting the electromagnetic field of a received signal and resulting in azimuth reading inaccuracies which are greatest between the four cardinal points with respect to the centerline of the aircraft.
848. COMPENSATION FOR QUADRANTAL ERROR.
It will be necessary to check the direction of the radio bearings every 45 degrees from the fore-and-aft axis of the aircraft (preferably Chap 15
AC 49.13-1А 1972 every 15 degrees) after installation of the loop in order to determine and compensate for the deviations caused by distortion of the radio field pattern due to the wing, engine nacelle(s), antennas, and other parts of the aircraft. If the loop is of the type which includes compensating means, it is important that no compensation be present in the loop at the time this calibration is made. If the loop has no provision for adjustment of quadrantal error, the calibration data should be used for the preparation of a correction card to be mounted in the cockpit near the indicator to provide the pilot with corrected bearing information.
849. GROUND CALIBRATION. The calibration may be made on the ground for installations in which the loop is on top of the aircraft, but the accuracy of the calibration should be checked in the air. However, for installations in which the loop is beneath the fuselage, the use of the flight method is necessary if accuracy is to be obtained.
850. AIR CALIBRATION. Air calibration of loops are best made on a day when the wind is less than 8 miles per hour and the air is smooth, using a medium or high-powered radio station between 25 and 100 miles distant. The station should normally provide good bearings with little or no fluctuation of the indicator pointer.
Do not make the calibration within two hours of sunrise or sunset or when wide fluctuations of bearings are noted.
851. CALBRATION POINTS, Select a landmark or series of landmarks such as & road, railroad tracks, section lines, etc., which will provide a Chap 15 Passe 301 direct line toward the radio station. Powerlines and railroads on or adjacent to the landmarks can distort the radio path, so make a check to determine whether or not distortion is present.
This can be done by crossing the reference line at various angles while maintaining fixed courses by means of the directional gyro. If the bearing changes rapidly as the line is approached, distortion is present and should be eliminated by flying at a higher altitude, or by selecting a new reference landmark.
852. CALIBRATION PROCEDURE. Fly directly toward the station along the reference line with the aircraft in level flight at an altitude low enough to avoid parallax error. When passing over some predetermined point or intersecting line to the reference, record simultaneously the indicator bearing and the directional gyro reading. Repeat the above procedure until sufficient readings have been taken at all required bearings. Since the radiocompass deviation changes to some extent with frequency, take calibration data at several frequencies to ensure greater accuracy in use.
853. CALIBRATION DATA. Calibration data obtained for a particular type of airplane is usable without modification for all aircraft of that type if the location of the loop and other antennas are the same. Since all sircraft of the same type may not have the same radio installations, an accurate diagram with antenna dimensions and exact loop location will add to the usefulness of the recorded data.
854.-863. RESERVED.
Par 848
AC 43.13-1A Page 303 1972 Chapter 16. INSTRUMENTS Section 1. MAINTENANCE OF INSTRUMENTS
864. GENERAL. The complexity of modern instruments, integrated flight systems, autopilots, sir data computers, and inertial guidance systems necessitates complex maintenance procedures, sophisticated test equipment and qualified personnel. The safety of aircraft operated in the National Airspace System is dependent in a large degree upon the satisfactory performance of airborne instrument systems. It is, therefore, important that maintenance be accomplished using the best techniques and practices to assure optimum performance.
The term "system" as used in this chapter means those units of power source, sensors, transmitters, indicator, and controllers which together perform a function of display, interpretation, or control of the functions of an aircraft, its systems or the environment in which it operates.
865. DEFINITION. The definition of an instrument is contained in Part 1 of the Federal Aviation Regulations.
866. MAINTENANCE OF INSTRUMENTS. Repairs and overhaul of aircraft instruments should be made only by an FAA approved facility having proper test equipment, adequate manufacturer's maintenance manuals and service bulletins, and qualified personnel. Details concerning the repair and overhaul of various instruments differ considerably. Test, repair, and adjust instruments and instrument systems in accordance with the manufacturer's maintenance instructions, manuals, and applicable F'ederal Aviation Regulations. Consult the airframe manufacturer for specific maintenance instructions involving instruments that are installed or supplied by them.
867. TEST/ADJUSTMENT OF INSTRUMENTS. Certain instruments, such as altimeters and vertical speed (rate-of-climb) indicators are equipped with simple adjusting means. They are readily accessible and do not require any special tools to operate. The adjustment should be accomplished by qualified personnel, using proper test equipment and adequate reference to the manufacturer's maintenance manuals.
a. The Altimefer. Most altimeters can be reset to correlate the barometric scale with the altitude indication using only a screwdriver. Manufacturer's instructions usually caution that this operation be done only once or twice. Under FAR 43.9, the event must be properly recorded in the aircraft's permanent maintenance records. Only small corrections should be made.
Large corrections should be regarded as an indication of possible malfunction of the instrument and appropriate tests be made.
(1) When correlating the altitude indication with the barometric scale, it is recommended that only two small adjustments be made without a scale error test.
(a) On initial installation of a new or properly overhauled instrument, a correction of up to 40 feet may be made.
(b) After the first flight, or series of flights, an additional correction of up to 40 feet may be made.
NoTE: Allow the altimeter approximately 8 hours to stabilize at the prevailing atmospheric pressure before making this adjustment.
(c) If an adjustment of over 40 feet, or any adjustment other than (a) and (b) above is needed, the altimeter should be sent to an instrument repair facility for testing, or should be tested in accordance with subparagraph (4) of this paragraph.
(2) To determine if a scale error test is necessary, rotate the barometric setting knob Chap 16 Par 864
until the CURRENT altimeter setting is indicated. The altimeter setting should be obtained from an FAA control tower or other accurate source. Compare the altimeter reading with the known altitude. A scale error test should be made, after adjustment, if the difference is greater than 40 feet.
Nore: Exact altitude of the altimeter should be determined, since the elevation from point to point on an airport may vary by a substantial amount.
(3) A recommended procedure for setting the barometric scale to correlate with altitude is as follows:
(a) Rotate the barometer setting knob until the altimeter indicates the known altitude. (See note above.)
(b) Following manufacturer's instructions, release the locking mechanism of the barometric setting device. Making sure the barometric setting knob is not rotated, pull the knob out until it is disengaged from the internal gearing.
(c) Rotate the knob to the CURRENT altimeter setting, then gently press the knob back until the internal gearing is meshed and engage the locking mechanism.
(d) Check the operation of the barometric setting mechanism by rotating the knob. Movement should be smooth; no grinding or sticking should be apparent.
(e) Rotate the knob to the pressures indicated below. The altimeter reading should change as shown within +25 feet:
81.00" Hg .. + 910 feet
30.00" Hg .. Reference setting
29.00i Hg .. - 986 feet
(4) If an adjustment exceeds 40 feet or any adjustment other than (1) (a) and (b) of this paragraph is needed, the altimeter should be tested for scale error. Air carriers' altimeters are tested in accordance with their approved maintenance procedure and all other altimeters in accordance with Appendix E, Part 48, using test equipment whose description and maintenance are at least equivalent to that contained in Advisory Circular 48-208A.
b. Vertical Speed Indicators. Most vertical Par 867 AC 43.13-1 192 speed indicators can be set to zero by mean of a slotted shaft adjustment, using only screwdriver.
(1) It is recommended that only two adjust ments be made without & scale error test Under FAR 48.9, the event must be properl recorded in the aircraft's permanent mainte nance records.
(a) On initial installation of a new o properly overhauled instrument, a correctio of up to 5% of full scale may be made.
(b) After the first flight, or series o flights, an additional correction of up to 5% of full scale may be made.
Nore: Allow the instrument approximately 16 minute to stabilize at the prevailing atmospheric pressure be fore making this adjustment.
(2) If an adjustment of more than 5% o any adjustment other than (1) (a) and (b) o:
this paragraph is needed, the instrumen should be tested for scale error. Air carriers vertical speed indicators are tested in accord ance with their approved maintenance proce dure and all other indicators in accordanc with manufacturer's procedures, using tes equipment whose description and maintenance are at least equivalent to that contained in Advisory Circular AC 48-208A.
868. REPLACEMENT OF COMPONENTS. Replac damaged or defective instruments with identi cal serviceable components or component equivalent to the original in electrical ano mechanical characteristics, operating toler ances, and the ability to function in the physical environmental conditions encountered in the operation of the aircraft. Be sure al shipping plugs and gyro caging devices that may have been installed for shipping purposes are removed before installing an instrument Check new installations carefully prior to applying electrical power or connecting test equipment to avoid damaging sensitive mechanisms. Test the new instrument after installation for proper functioning (where applicable).
869,-879. RESERVED.
Chop 16
C 43.13-1A Fage 305 172 Section 2. INSPECTION AND CHECKS
80. GENERAL, Proper operation of aircraft astruments is important to safe flight. Inpection is an important part of instrument maintenance. Inspection of instruments and nstrument systems should include at least the ollowing items (where applicable) :
a. Inspect external pitot-static equipment for ›oor condition, cleanliness and deformation.
b. Inspect instruments for poor condition, nounting, marking, broken or loose knobs, bent r missing pointers, and (where applicable) mproper operation.
c. Check power-off indications of instrument ›ointers, tape scales, and warning flags for proper indications.
d. Apply power and check for excessive mehanical noise, erratic or intermittent operajon, failure to indicate, sluggishness or indicaion of excessive friction.
e. Check that erection or warmup time is not excessive, caging functions are normal, and warning flags and indicating lights and test circuits are operable.
f. Note the operation of instruments during engine runup (where applicable). Check for intermittent or improper operation of any instrument.
g. Inspect all systems for improper installation, poor general condition, apparent and obvious defects, and insecurity of attachment.
B81. PERIODIC INSPECTION. Periodic inspections should be performed in accordance with applicable parts of the Federal Aviation Regula-
882. ADDITIONAL INSPECTIONS. Periodic inspections may be supplemented by additional inspections based on the intended function of the aircraft and frequency of use. These additional inspections may be performed at any time to help maintain an airworthy aircraft.
A suggested list of additional items is:
a. Check tubing connections and airframe mounts for security and condition.
b. Check pneumatic tubing for leaks, corrosion, erosion, cracks, bends and pinching, and evidence of chafing.
ange of lumination urned out bules, to defective controls.
d. Check electrical connections, fuses, fuse clips and circuit breakers for proper size, security and condition.
e. Check wiring for excessive bends, chafing, excessive tension, improper support or broken lacing and ties.
f. Check for evidence of overheating or contamination of equipment by foreign matter or water. Dust, dirt, and lint contribute to overheating of equipment, poor ventilation, and malfunctioning. Special attention should be given that ventilation openings in equipment housings are open and free from obstructing lint and dust.
883.-893, RESERVED.
Chap 16 Par 880