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Engine and Airframe Technicalities
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Contents:
…Unfamiliar Systems; …Differential Pressure Check; …Manifold Pressure and More; … A&P Inspection Authorization; ...AI Authorization; …About the Annual Inspection; …Annual Inspection by Checklist Phases; …Part 145 Repair Station; ...FAA Approved Interior; … Maintenance Program; …Owner/Mechanic Relations; Owner Produced Parts; ... Common Maintenance-Related Causes of Errors; ...Corrosion; ...Corrosion Control for Aircraft; ...On Owing an Aircraft; ...Basic Aircraft Ownership; ...IOPPSS is here…Owner Preventive Maintenance; ...Fabric; ...Jump Starting; 

Unfamiliar Systems
Interestingly there are at least fourteen distinct systems that are required knowledge for the pilot. Usually lost in the morass of the others because it comes into play only twice per flight is the restraint system. Have you ever considered the safety harness system consisting of seat belt and shoulder harness as a distinct system. A system requiring operational specifics related to FARs, instructional usage, limitations and emergencies. The first emergency I ever felt and declared was when a thin student let the seatbelt end hang out the door so it could flap and snap against the underside of the aircraft.

The FARs require that the pilot brief all passengers about the use of seat belts and notifies them when the belts are required and how to release them. This requirement is irrespective of the prior qualifications of the passenger. Seatbelts briefings in the FARs are required only for takeoff; notification about the seatbelts is required for takeoffs, landings and all surface movement. In a single engine aircraft only one person can preside as a required crewmember. This required crewmember must keep his seat belt and shoulder harness fastened while on his duty station. The shoulder harness is not required where it may interfere with piloting duties.

Passengers are not required to use seatbelts or shoulder harness while en route. Only in the FARs would the requirement that passengers be required to be briefed as to the use of belts and harness, without any requirement that they be worn. Dumb and dumber.

The vacuum system is one of the most reliable and limited use systems used on aircraft. Usually, it only serves to operate the attitude indicator and heading indicator. Early on it consisted only of a venturi 'horn' on the side of an aircraft to provide in motion vacuum. Now, replaced by a engine driven vacuum pump the 'horn' is usually a curiosity.

Instructional aid:
The simplest demonstration of venturi action coming from accelerated air and lower pressure can be done with two sheets of paper. Suspend each sheet from one end between the thumb and forefinger of both hands. Hold the sheets about two inches apart so that you can blow between the sheets. Blow and observe that the sheets close together. You have created a venturi and made it work as such. Put a few drops of gasoline on the back of your hand and then wave the hand about. Notice the cooling effect. With these two experiments you have most of the essentials for carburetor icing. Lacking are only the evaporative powers of the fuel and the presence of moisture. Try it.

One specific about the pump is that it will run for about 600 hours once it survives the first couple of hours. It is usually replaced upon failure and not as a precautionary measure. Most are dry but some are wet (oil) and tend to fail gradually so that it may be so subtle as to escape notice. When this occurs in IFR conditions bad things can happen like fatal accidents.

Be able to diagram the pitot-static system, which involves two separate holes in the exterior of the aircraft. The pitot tube is a measure of air pressure caused by the aircraft's relative wind. This tube goes to the airspeed indicator to create indicated airspeed. The static air hole goes to the altimeter case and the vertical speed indicator.

The aircraft environmental system is made up of two separate systems. Cabin heat comes from air that is contained in a muff welded around the engine exhaust pipes. This is a relatively simple method of benefiting from excess engine heat. However, should an internal crack develop in the exhaust pipe inside the muff, carbon monoxide will become a part of your cabin heat.

Interestingly, even without any leakage of exhaust gases it is possible for a tightly sealed cockpit to trigger your carbon monoxide detectors due to the lack of cockpit ventilation. I recently had such an event with only two people in the cockpit. It would be wise to ventilate aircraft cockpits at all times.

A part of every aircraft checkout should include the full information of the heating system and any associated dangers. Cabin vents are located in several difference places and with varied modes of operation. Some vents are best not used in rain for obvious reasons. The restrictions related to opening windows and doors is a part of this system.

I have rarely entered an unfamiliar aircraft that I have not experienced some peculiarity of avionics system be it switch, knob or other operation. Recently sat next to a Cutlass where the pilot spent at least ten minutes trying to figure out the radios before shutting down. The presence or absence of a radio master makes a difference in operational procedures. Radio switches are the most vulnerable to defective operation. The first item to suspect when you have a problem is yourself.  Check your headset cables, then any frequency setting, then the audio panel settings and then the volume. Test your settings with the ATIS. The failure of the avionics is not life threatening even in IFR Use a standby handheld or just proceed to nearest airport using NORDO procedures.

The electrical system consists of multiple sub-systems in which each has a number of switches. The starting system consists of the battery, a master switch, a starter solenoid, the starter with attached Bendix spring and the key switch with start, both, left and right selections. The lighting system consists of interior, exterior, landing, navigational, strobes, indicator, and warning lights. All of these sub-systems have their own switches, operational criteria and useful significance. The pilot is expected to know the use, operation, significance and applicable FARs for every light.

The electrical system is usually involved with varied capability in the aircraft trim, flaps, anti-ice, environmental operation. Each sub-system is fused or with circuit breakers. The pilot must know the process required to maintain electrical operations and how to replace fuses and reset breakers. Just as important is the pilot's willingness to leave an existing situation for more qualified personnel.

The landing gear system involves the gear box attachment as well as the shock system, wheels, bearings, brakes and tires. The pilot must be sensitive to the operational limits of the gear. Side loads are damaging. Heaving braking ruins tires and wears out brakes. Wheels can be broken by hard landings. Improper inflation is the most common reason for an aircraft being operated in an 'unairworthy' condition. A pilot is expected to know about the gear and its peculiarities.

While the brakes are part of the landing gear, the operation of the brake is an independent hydraulic system similar to that used in automobiles but with smaller and lighter components. A pilot is expected to know how the hydraulic fluid is different from other fluids in the aircraft. Being able to check brake operation and fluid levels is, or can be, part of the preflight. Brakes are a relatively frequent responsible component of aircraft accidents. Aircraft braking is best done in light smooth applications rather than pumping. Heavy braking will over heat the pads and reduce effectiveness. Turning while braking will put damaging side loads on the wheels and gear boxes.

The fuel system consists of the tank(s), tank caps, plumbing, selector and cut-off valves, quantity indicators, pressure system and distribution method to the cylinders. Fuel octane is a prime operational requirement determined by the engine manufacturer. The pilot is expected to be able to compute and predict fuel consumption for the aircraft in terms of weight, capacity, quantity, and time. The fuel is metered through a mixture control in conjunction with a throttle. The throttle functions by changing engine power much as in an automobile but the effects on the aircraft performance are often contradictory. The mixture us a fuel weight adjustment based upon the weight of air available to the engine through the carburetor. Efficient aircraft operation depends upon the pilot's knowledge of and use of the fuel system. Excess fuel can be used as a coolant.

Oil is used as part of the engine lubrication and cooling requirements. The pilot must make sure to use the correct weight and type of oil to best protect the engine. Only special oil systems work inverted. Oil quantities are registered on the dipstick, which must never be overly tight. Expansion of the oil filler tube can cause the cap to stick so tightly that the tube will unscrew instead of the cap. Only finger tight is best.

The aircraft propulsion system includes the engine, its auxiliary components and the propeller. The type of engine and its definition in terms of letters and numbers used by the manufacturer are required pilot knowledge. The propeller is a special system on its own with its own maintenance ADs independent of the engine and aircraft. The care and feeding of the engine and its accessories is required knowledge of the pilot. Knowing the length, pitch, and any special characteristics of the propeller range in importance from the nice to know to the need to know.

The flight control system consists of two levels. Primary will be rudder, ailerons and elevators. Secondary will be flaps and trim. The pilot is expected to know how each of these affects flight independently and in conjunction with the other controls. Some aircraft have specific modifications that are on the wings or other surfaces. If your aircraft has any modifications, you are expected to know what they are for and how they accomplish their intended purpose.

Differential Pressure Check
The purpose of the differential pressure check of a cylinder is to determine its relative health. As in medicine, the test alone proves little, it is the interpretation that determines if a problem exists. The engine is brought up to operating temperature before the test begins. The complete picture requires analysis of the oil filter, oil consumption rates, and oil analysis.

The process begins with removal of the top sparkplug. The piston is brought to top-dead-center by turning the propeller (magnetos are off). The regulator is positioned into the sparkplug hole and compressed air is allowed to enter until it reads 80 pounds. The propeller is held to prevent any movement.

The mechanic is waiting to see how much of the initial air pressure can be retained in the combustion chamber. If the pressure stops dropping at 70 the figure 70/80 is usually written on the cylinder. If the pressure drops to 60 concerns arise. Where the air escapes tells if the problem is rings, valves or cylinder wear. This compression check will unveil a cracked cylinder or head. False problems can be caused by ring alignment or contamination.

Manifold Pressure and More
A high MP low RPM setting uses less fuel than a low MP high RPM setting for the same output power. The energy required to overcome pumping losses makes the difference. The further open the throttle the less work the engine has to do moving the pistons against atmospheric pressure on the intake stroke.

Power in an engine is the product of Manifold pressure, displacement, and RPM. We can vary Manifold pressure and RPM, but displacement is fixed. Performance is determined by available power. The air volume and density used by the engine is determined by RPM and displacement. The lower the MP the lower the air density in the intake manifold, and the less air is moved at any given RPM. RPM has a greater effect on the amount of air than does MP. A higher RPM for any given power will result in more fuel burned for that power.

Since POWER is proportional to the product of MP and RPM you can get the same power at many different combinations of the two. You can increase MP and decrease RPM and keep the power the same. The lowest fuel consumption for any given power output would be at the combination that gives the highest MP and the lowest RPM. An increase in MP and a lower RPM will increase the pressure and temperature inside the engine. You will eventually reach the pressure point where detonation occurs. You will ruin the engine if it continues this operation.

The POH gives operational figures that preclude detonation. The figures that have highest MP/lowest RPM give the lowest fuel burn for the power setting. Higher altitudes will reduce the available MP. As you climb a higher RPM will be required to reach or maintain the power percentage desired. At 7500 feet and full throttle will give you 75% power for a normally aspirated engine.

A&P Inspection Authorization
--Is A & P who is responsible in assuring of highest levels of trust, responsibility and values of the A & Ps.
--Inspection Authorization under FARs..
--65.91 Applicant must meet requirements and is actively engaged in aircraft maintenance (35 hours a week with a work place phone number)
--65.92. Every March 31 IA must be renewed.
--65.93 Must perform one annual inspection for every 90 days certified, two major repairs or alterations, a progressive inspection , taken eight-hour renewal meeting, or oral quiz by FAA inspector
--65.95 AI can perform annual inspections, supervise progressive inspections. inspect major repairs, inspect major alterations. notify FSDO of any change in AI location.

AI Authorization
The Federal Aviation Administration, reposing special trust and confidence in your integrity, diligence, and discretion and finding that he or she has the necessary knowledge, skill, experience, and impartial judgment, to merit special public responsibility the FAA, now grants/renews your Inspection Authorization.
History
-- The AMEs were the first designees
--Pilot designees appeared in 1941.
--FAA created in 1958 along with annual inspection requirement.

About the Annual Inspection
--Get several references for any AI before you get involved.
--Having every annual inspection done at the same place may not be wise.
--Owner should pre-arrange right to participate and not pay AI to watch work being done.
--FAR Part 43 lists inspection items required.
--The annual is an inspection only by a mechanic with an inspection authorization using a checklist.
--Inspection is complete when aircraft logbook entries are completed by the AI.
--AI's opinion cannot be appealed only complied with.
--AI can be expected to document every decision by means of specification and documentation.
--All items making aircraft unairworthy are listed as a part of the inspection logbook entry.
--It is an expensive mistake to stop the inspection to fix a discrepancy. Complete inspection then repair.
--Any AD's must be complied with and logged properly.
--Owner is responsible for compliance with AD's as to when, where and how compliance was performed.
--Repair requires a certified mechanic. The AI and the A&P need not be the same person.
--A&P must make logbook entry certifying aircraft safe for ferry permit flight …or
--A&P must make logbook entry certifying all of AI's entries have been complied with and aircraft airworthy.
--Final responsibility of airworthiness lies with owner. Airworthiness is determined before each flight.
--Aircraft must meet specifications of type certificate in equipment and tolerances of components.
--AC 43-13 gives approved repair procedures

Annual Inspection by Checklist Phases
--Paperwork and ADs
--Past records reviewed
--Compliance with all ADs confirmed on plane and in logs
--New and recurrent ADs added to checklist
--Class I appliances (major components) type certificate data sheet (TCDS), STC and alterations comply.
--Run-up and systems
--Washing and disassembly
--Inspection
--Table of limits and specifications to determine if serviceable
--Preventative maintenance
--Owner can do preventative maintenance if IA inspects work
--Lubrication and adjustments are part of preventative maintenance
--Reassembly
--Owner can disassemble and assemble as long as AI inspects procedure
--Post-annual run-up and systems check
--Logbook entries
--When inspection is complete unairworthy items must be corrected before airplane is returned to service
--Research inspection items to confirm tolerances specified
--AI must list all discrepancies
--A & P must complete log for every discrepancy satisfied.

PART 145 Repair Stations
--Created in 1939
--Regulations codified in 1962
--5000 repair stations exist
--New 2001 rule is 151 pages long at http://www.faa.gov/avr/arm/proc.htm Docket # FAA-1999-5836
--Effective date is April6, 2003
--Contains new terminology and definitions
--Requires quality control of work and parts
--Requires stable location
--No change in certification of repairmen or operating specifications

FAA Approved Interior
--Only FAA certified items and materials can be used on or in an aircraft.
--Only original or certified at meeting type requirements materials can be used.
--Any installation must be capable of being inspected and maintained.
--A minor change uses acceptable recorded materials and parts such as originally used.
--Aircraft materials must be flash resistant and flame resistant by certified test.
--Approved FAA Repair Stations can perform the Part 23 burn test and recorded in logbooks.
--Keep all records, invoices and samples of materials and an additional set separately
--A major change uses material or parts that require creation of data for acceptance.
--Approved data requires check by rated Designated Engineering Representative, an STC or field approval.
--Any STC includes instructions for maintenance and Instructions for Maintaining Continued Airworthiness  (IMCA)
--The IMCA are put into the logbooks along with a replacement parts list.
--Interior installation and maintenance requirements are the most frequently overlooked airworthiness requirement.

Maintenance Program
--Immediate
--Leaks
--Wet brake calipers
--Baffles
--Tire pressure
--Get fixed whatever needs fixing

--Post-flight
--Exhaust pipe check
--Magneto check
--Gear and tires

--Pre-annual
--Fuel Selector
--Heater
--Control linkages
--Corrosion

--Occasionally
--Oil change
--Under cowl check
--Lights
--annunciators
--Avionics currency

--Constant
--ADs
--Anticipation of parts needed
--Unusual event in operation
--In aircraft spares, lights, drains,
--IRAN items for mechanic (Inspect and Replace As Necessary)
--Anticipation of failure beats waiting for failures

Owner-Mechanic Relations
--Be interested
--Be accessible
--Bring money
--Accept advice
--Owner hands-off except for Part 43 list.
--Use only approved materials and parts
--Pay the price for the best.
--Log all work properly
--Proper operation is a preventative maintenance measure.
--Most wear occurs just getting started.
--Cold is hard on aircraft.
--Plan your route for best survival options.

Owner Produced Parts
--Only option for older aircraft.
--Owners are allowed to make parts but they cannot install unless an A&P
--A&P must certify the quality of the part.
--Five limitations:
--Aircraft owners are the only ones allowed to produce new parts.
--Participation in the manufacture is required of the owner in one of five possible ways.
--Part cannot be installed unless it meets all four of new part characteristics.
--Determine where a repair becomes a new part may require an FAA FSDO opinion.
--Final decision and responsibility rests with mechanic.
---A & P can make a repair or install but not MAKE a part.
--The 'test of reasonableness' may determine what makes a 'repair'.
--Published and available material specifications exist.
--Part is simple and fabrication uses tools and standard industry procedures.
--Templates for design are available.
--Parts and repair is in accordance with manufacturer's instructions.

Part must have characteristics of an approved part:
--Part must be an FAA approved design:
--Drawings, specifications, design, and configuration are defined.
--Strength is defined by materials, dimensions and processes.
--Given airworthiness limits and instructions to maintain airworthiness.
--Data needed to determine airworthiness of later same type products.
--Part must conform to design
--Has all structure needed for the design
--Conforms by materials and specifications
--Conforms to drawings
--Identical manufacturing, construction, and assembly.
--Part has documented production and FAA approval
--Part must be maintained under FAR Part 43

FAR 21.303(b) 2 lets owner make part to maintain or alter his aircraft part. The Owner Produced Part must be installed by on the owned aircraft and cannot be made for sale.
Ways a New Part Can Be Made:
--Parts Manufacturer Approval
--Technical Standard Order
--Type Certificate or Supplemental Type Certificate
--Type Certificate with Approved Production Inspection System
--Production Certificate
--Bilateral Agreement
--Any method acceptable to the Administrator
--Standard Parts
--Owner Produced Parts
--Parts per Supplemental Type Certificate instructions as part of Supplemental Type Certificate modification
--Fabricated by qualified person as repair to return Type Certificate part to service but not for sale. Part 43

Common Maintenance-Related Causes of Errors.
Major Cause--Lack of Communication between people.
1) Complacency
3) Lack of Knowledge
4) Distraction
5) Lack of Teamwork
6) Fatigue
7) Lack of Resources
8) Pressure
9) Lack of Assertiveness
10) Stress
11) Lack of Awareness.
12) Norms

Corrosion
--Destruction of metal by electrochemical reaction is called corrosion
--Water is the electrolyte with metals such as magnesium, steel and aluminum making either the anode or cathode.
--For more: www.corrosion-doctors.org

--FAA AC 43-4A Corrosion Control for Aircraft
--Aircraft corrosion begins the moment the aircraft is being assembled.
--Corrosion inspection is not (normally) a part of the annual.
--Only waterproofing such as paint or zinc chromate prevents corrosion.
--There is more corrosion inside than outside the airplane.
--Blistering paint is the first obvious sign.
--Black smudged power on trailing edges of rivets and white patches on aluminum are common signs.
--Usually on access panels, hinges, access doors, window seals and windshields
--battery area, (escaping gasses), door panels, insulation areas, steps,
--Wash with aviation products never automotive.
--Cockpit cover is good investment
--Corrosion inhibiting compounds (CIC) can interrupt the process.
--Barrier-coat finishes
--Zinc Chromate is heavy, hard to remove and effective

Semi-hard coatings:
--lighter, easy to use, penetrate, flexible, self healing, effective
--Fluid-thin coatings
--2/3-year life, penetrant, displaces moisture, transparent, oil that displaces moisture
--Application can be owner maintenance or $400 professional.
--Logged applications add to value.

On Owning an Aircraft
--Hangar time counts more against you than the airplane.
--Set realistic (longer) time goals for any major aircraft work.
--What you want is affordable airtime.
--You must determine whether or not to accept your cost for flying.
--FAA maintenance standards are minimum standards.
--Logbooks often reveal more by what is not there than by what is written.
--Don't mess with an aircraft that can become or is too expensive.
--Flying becomes expensive when your wants exceed your needs.
--Time spent not flying is a cost above money.
--You increase the cost when learning is combined with the doing.
--A knowledgeable expert is most often worth the money.
--Good news means that something exists, bad news is the cost.

Basic Aircraft Ownership
---Join a ‘Type Club’ for learning about maintenance, repair, operations or upgrades.
---Join a ‘Regional Group’ for best local information, sources, forums’ things to do and not to do.
----Learn to do your own oil changes, inspect the interior of the filter and log what you have done.
---Get oil analysis at every oil change.
---Your maintenance logs are half the value of the aircraft.
---Have mechanics give you self-adhesive labels for any logbook entry for you to put into the book.
---Owner assisted annuals is the only way to go regardless of what you are told.
---Get CD/CDROM manuals for your specific aircraft and keep a copy with the aircraft. adds value
---Fly the plane correctly and regularly
---Ownership is not for the faint of heart or weak of wallet
---Learn to judge a problem as small and flyable vs large and grounded.

IOPPSS IS HERE
Industry Operations Specifications System is a computer maintenance system that allows maintenance people to amend and sign OpSpecs for FAA inspector approval over the internet. OpSpecs are a legal contract based on special authorizations and limitations of the certification. The combination of software and electronic signatures make everything FAA legal for a fee.

Owner Preventive Maintenance
The FAA regulations within 14 CFR Part 43 cover preventive maintenance,
rebuilding, and alteration. More specifically, Section 43.3(g) states
that the holder of a private pilot certificate may perform preventive
maintenance. There are 32 owner-performed maintenance tasks outlined in
Appendix A of Part 43. The oil change is one of the most common owner-
performed tasks. Consider asking a local mechanic to walk you through
the first oil change and show you anything specific about your airplane.
Also, check with the airport manager to find the best location to set
up shop. You will need to make an entry in the engine logbook. A
recommended sign-off is provided in AOPA's "Pilots' Guide to Preventive
Maintenance" ( http://www.aopa.org/members/files/guides/maintenance.html ).
You should also consult the appropriate service manuals and manufacturer's
service publications before getting your hands dirty. But do not go
beyond the 32 allowed maintenance points, which could result in an FAA enforcement action and invalidate your insurance.

Fabric
James H. Macklin
ATP,CFI,A&P
The makers of the FABRIC and the FAA have procedures for
inspecting fabric, see AC 43-13-1. Get the catalog from
Aircraft Spruce http://www.aircraftspruce.com/ It has a lot
of good info.

The manufacturers have recommendations for areas to check on fabric covered airplanes. Sunlight (UV causes most damage) which is why the layer under the color coat is silver (aluminum powder in clear dope) to block UV, also chemical and mechanical damage must be checked at each annual. The mechanic will typically use a punch test to see how many pounds are required to penetrate the fabric when the dope is removed from the small areas that are critical. On old fabric or if the fabric is questionable, samples are removed and sent to a laboratory for full testing. The standard fabric repairs are made to the areas tested. Fabric such as cotton, Dacron, fiberglass and others are FAA approved. The different fabrics have different life and require different types of paint and dope.

Dave Stadt" <dhstadt@ameritech.net> wrote in message
news:ufAAf.15699$Yu.11372@newssvr27.news.prodigy.net...
"Michael Horowitz" <mhorowit@cox.net> wrote in message
news:poa5t1trirkkmv09q1q20aj2h6jm2mn4ak@4ax.com...
In discussion elsewhere, folks are suggesting that every 20 years or so the fabric should come off a fabric/steel airframe in order to inspect areas un-inspectible with the fabric intact. This suggestion is proposed even if the fabric appears sound.

|If there are un-inspectable places on an airframe, how did you find an | > A&P to accept the liability and sign off on an annual? Or are failures in the un-inspectable places not a big problem? - Mike

How many people take spam cans apart to inspect the areas that are hidden? | There are hidden places in all aircraft that cannot be seen or inspected. | For instance spam can wings. Have never heard of anybody pulling the skins | off a spam can wing for a look see unless it is for accident damage.

It does make sense to open a tube and fabric tail dragger that sits outside | as moisture tends to run down and rot lower tubing and tubing near the | tailwheel. Although, you can usually see the rust and corrosion as rough spots in the fabric where it touches a tube. But, how many planes like that spend any amount of time on a tiedown and not in a hangar. No need for a hangared plane to come apart if it is kept clean and dry. Best way to keep everything dry is to frequently fly the airplane.

Jump Starting
----- Original Message -----From: "Bev Revak" <bvr@centurytel.net>
To: <gwhitt@ix.netcom.com>
Sent: Thursday, February 02, 2006 8:06 PM
Please cover jump starting a Cessna 150.

Bev,
There is a FAR violation possible in any jump starting. So my suggestions must warn you that  A C-150 that will not start using the battery, if the FAA chooses, would be considered unairworthy.  Don't let anyone but an A&P help you jump start. The LINEBOY is not an A&P.  Have the FBO install another battery.  You would be better off to have an experienced pilot at the controls inside the plane

That said
I found Three applicable Entries on my site
Engine Starting (two times+) on Page 2.3
Hand propping Page 3.13

The very best was Hand propping with a low battery Page 5.98.  I had an A&P go through this procedure so that the engine started with the propeller only moving one foot using battery power.

If this doesn't meet your needs, email me
Gene Whitt
Bev responded that the info was requested as part of her expected oral questions on a checkride.

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