Lighten the load of an aircraft

All aircraft have a maximum gross weight for safe operations. Weights are checked before the airplane takes off, and the pilots occupy themselves with all that is involved in flying the airplane. Sometimes something goes wrong in flight, and the plane is may be too heavy.

Allow me to tell a couple of stories to illustrate.

I have been reading about WWII bombers including the B-17 and the B-24 for some future articles for this blog. I have read some accounts of a heavily damaged bomber making her way back to base. Perhaps an engine was out and the performance of the bomber was suffering. Once they back in friendly territory and no longer at risk for being shot down in enemy territory, the pilot had to find a way to lighten the aircraft to have the best odds of returning to base. So, he would order the crew to dump equipment, armament, etc. overboard. The now lighter aircraft may be able to make it back to base. Or at least land or ditch in friendly territory.

Several months ago a commercial airliner got in trouble shortly after take-off. If memory serves, they had a hard time retracting their landing gear. They had to return to the airport, but they were too heavy to land. Procedures called for the pilots to jettison some fuel until a safe landing weight was reached. They circled at a safe altitude for something like 20 to 30 minutes. The fuel evaporates in the air, well before it reaches the ground. After the safe landing weight is reached, the pilot returns to the airport for an emergency landing. Emergency vehicles are on alert. The landing gear holds and the pilot brings the plane down safely. No injuries and fatalities. The passengers deplane and catch a later plane to their destination.

I believe that I was about three or four months into writing about aerial wildland firefighting when I first learned that all (or most) tankers and helo pilots have the capability to jettison a full load of retardant when an emergency arises. Such emergency situations where the tanker pilot will jettison a load of retardant include an engine failure, and getting caught in bad winds. Of course there are important considerations here before jettisoning the retardant because the weight of falling retardant can kill people on the ground so a tanker pilot will not make an emergency drop if there are folk on the ground in the path of the emergency drop.

I have some numbers for you to demonstrate the weight of the retardant. That will come in my next post. If the weather and the power grid allow, I hope to be making this post on Wednesday.

Erickson Aircrane revisted

I am a little under the weather so I did not make a post yesterday. I hope to be back in a day or so. In the meantime, enjoy this video, probably a repeat, of the Aircrane, Isabell, piloted by Kenny Chapman, working the Backbone Fire in the Six Sisters National Forest in July 2009.

Aircraft tire pressure and hydroplaning

A couple of weeks ago, a friend of mine sent me an article on the importance of properly inflated aircraft tires, it may be found here. This got me thinking about the importance of properly inflated aircraft tires. While the article that my friend sent me talks about improperly inflated tires as a cause of the crash of a Lear Jet and a commercial airline in the Middle East, it is important for all aircraft, from my Cessna trainer to Lear Jets to airtankers to Jumbo jets, to have properly inflated tires. I am going to talk a little about what I am learning about the importance of properly inflated tires on single-engine aircraft such as the Cessna 172 that I take scenic rides in.

I have recently been working on pre-flight inspections of an aircraft with the pilots that take me on scenic rides. The tires are one of a number of items on our pre-flight checklist. So, I told him about the article that my friend sent me. He told me that he thought that the proper tire pressure on the Cessna 172P was about 30 pounds per square inch (psi). He went on to remind me that we had talked about the relationship between tire pressure and hydroplaning and aircraft speed in ground school.

Automobiles can hyrdoplane, as can aircraft. Not a situation you want to be in either vehicle. When you hydroplane, for example on a wet runway, your tire loses contact with the ground and you lose control of the aircraft.

Take a moment and go here and watch a two minute video on NASA's work on hyrdoplaning. You will see a formula in the video:

9 * (the square root of the tire pressure) = the speed in knots at which you will begin to hydroplane.

According to the above formula, a tire with pressure of 30 psi will start to hydroplane at about 49 kts.

I learned a quick and dirty version of this formula in ground school:

(tire pressure &#247 by 6) * 9 equals the speed that aircraft will start hydroplaning.

Using the quick and dirty formula, the tire will start hydroplaning at 45 kts. I like that the number is a little lower than the 49 kts in the NASA video because you have a target safe landing speed that is a little lower. Perhaps providing a safety margin? But it is an easy formula for to remember, and you can do the calculation in your head (or on the pad of paper on your knee board).

The key here is that the lower the tire pressure, the lower is the speed that the aircraft will start hydroplaning. Using the quick and dirty formula, the number comes out to be 42 knots. If you land at 45 knots with tires at 28 psi on a wet runway you will hydroplane.

I don't know about you, but that short conversation with the pilot made an impression on me. I"ll leave it to the folk at NASA to do their tests and research on hydroplaning aircraft tires.

Note - apologies for not using proper mathematical notation for the square root symbol. If I can figure out how to include a square root symbol in html code that will show up here, I'll revise the article later.

More on Flooding in Australia

It is summer in Australia, and in other years it is around this time of year that the summer fire season down under would be ramping up. It was my intention to try to follow the 2011 summer fire season in Australia. They had been in a long term drought not so long ago. Things changed.

Sometime around the end of 2010 or early 2011 I first heard about widespread and catastrophic flooding in Australia. The videos I saw on the news were horrific. Words escape me and I wish that I could do something to help.

I suspect that given the moisture that will be present in the soil and the vegetation, even after these catastrophic flood recede, that the wildfire danger will be diminished. However, I am not exactly an expert on these matters. Nor am I familiar enough with Australian geography and weather patterns to know if there are areas in Australia that have not seen these flood waters that might be at risk for wildfires. I suppose that I'll find out as the summer months in Australia unfold.

That being said, I do want to provide a couple of resources for those of you who might want to see the effect of the catastrophic flooding in Australia. To that end, I am providing a couple of links. And here I am probably only touching the surface of coverage (media, personal accounts, etc) available on the internet.

1. Skynews Australia has a flooding webpage with reports and videos that may be found here.

2. A newspaper in Brisbane in Queensland AU, The Courier Mail has extensive coverage of the floods. This coverage includes, but is not necessarily limited to photo galleries (two may be found here and here, a story page with personal stories of devastation and hope, an interactive map of the Brisbane River Flood Crisis, and a link to a very good high resolution online mapping system of Australia that may be found here. And there are other links on the Courier Mail site that I am not including here.

Flooding in Australia

I would be remiss to not post about the devastating flooding in Australia. Words escape me.

Aircraft maintenance logs

My point in writing this short article about aircraft maintenance logs is to not to go into any kind of detail of on keeping the FAA required aircraft maintenance logs. Rather it is to write about something that I had never given much thought to -- aircraft maintenance logs -- until about one year ago.

At some point after I'd been writing about the world of aerial wildland firefighting for several months I had a vague awareness that detailed maintenance logs were kept for all (or most) aircraft. Then I went to ground school last winter and to learn various FAA regulations, including but not limited to the regulations for who can do what type of maintenance on an aircraft, who (airframe and power plant mechanics or airframe and power plant mechanics with inspection authorization) can do what type of inspection, and that maintenance and inspections are logged in the appropriate maintenance log(s).  Keeping maintenance logs for a given aircraft is not an option, it is required under FAA regulations. Furthermore, the logbook(s) are transferred when the airplane is sold.

It is not just one or two maintenance log books, but multiple logbooks. There is an airframe maintenance logbook. And there is one logbook each for each engine and propeller. So, the (single-engine) Cessna trainer that I go flying in has three logbooks. A tanker with four engines with four propellers (such as a P-3) will have four engine logbooks and four propeller logbooks.

FAA regulations specify certain preventive maintenance that can be performed by the pilot/owner. After the pilot completes the preventive maintenance item, s/he notes the repair in the appropriate logbook and then signs and dates the logbook. Likewise, maintenance completed by an airframe and power plant (A&P )mechanic  is logged in the appropriate log book and then signed and dated by the A&P mechanic. Inspections are also logged in the appropriate logbook by the A&P mechanic (with inspection authorization as appropriate) completing the inspections.

The FAA does not require that the maintenance logs be kept in the airplane. It is a legal document that must be available to the FAA, NTSB and other agencies within a specified time period when requested. It is not a good thing for the logbooks to be lost and/or destroyed. For these reasons the maintenance logbooks are usually kept in a safe place away from the airplane.

For those of you who never knew about maintenance logs until you read this article, perhaps the next time you see an aircraft, no matter how small (a Cessna trainer) or how large (a jet operated by an airline), you will know that there are multiple maintenance logs for that aircraft.

Progressive Inspections (2 of 2) -- A brief look at what happens in progressives

What might happen in a progressive inspection program? I don't have access to any current progressive inspection program documents, but thanks to discussions with friends who are airframe and power plant mechanics who have worked on progressive inspections, I have an idea of how progressives work.

In a typical FAA approved progressive program, the progressive is based on three or four operations that recycle after a certain number of hours. So lets say there is an approved progressive program , e.g. for a hypothetical single-engine fixed wing aircraft, has four operations occurring at 50 hour intervals, recycling after 200 hours (of flight time). Further, the progressive inspections must be completed within a twelve month period.

Lets say that the last twelve month period started on January 31, 2010 and the aircraft has only flown 140 hours to date with progressive inspection operations one and two already completed. Operations three and four must be completed by January 31, 2011.

There will be a list of specific items that have to be inspected in each operation. Each operation is likely to focus on detailed inspections of one or two components with routine inspections of the other components. For example operation # 1 may  have detailed inspection items for the landing gear and wings with routine inspection items for the rest of the aircraft (cabin, fuselage, engine, propeller, and empennage).

In my discussion of progressive inspections, I would be remiss if I did not mention that the FAA regulations mention that life-limited parts have to be replaced before the end of their life. I suspect, that life-limited parts will be replaced during progressive inspections. I also suspect that the replacement of life-limited parts is an important component of maintenance and inspection programs in the tanker business, whether they be progressive inspections or some other type of FAA approved inspection program.

As I have learned more about how progressive inspections work, I appreciate that the world of aircraft maintenance and inspections, including but not limited to progressives) is often complicated. A progressive inspection program in the tanker business is going to be much more involved and a lot more time consuming than a progressive for a fixed-wing single engine aircraft with non-retractable landing gear. Nothing is simple in the tanker business.

This ends my two-part series on progressive inspections. Perhaps I'll revisit progressives again in later articles. For now, I am moving on. In my next article, I'll write a little about maintenance and inspection logs.

Progressive Inspections (1 of 2) -- Why progressives?

An owner/operator of an aircraft can fulfill the requirements under CFR 14 FAR part 43, appendix D by having a maintenance and inspection done once a year, known as an annual, by an airframe and powerplant mechanic with inspection authorization. I'll be writing about annual inspections a little later. For now, I'll say that the FAA requires that the annual inspection be done at the end of the twelfth month following the last annual. So, if the last annual was done on Dec. 5, 2010 the next annual is due on or before Dec. 31, 2011.

An annual inspection for a Cessna trainer or similar general aviation aircraft might mean that the aircraft will be out of service for two or three days. The more complex the aircraft systems (including multiple engines), the longer the annual will take and the longer the aircraft will be out of service. For example, I suspect that the multi-engine airplanes used as tankers may be out of service for at least one month.

A private pilot who owns their own plane for personal or recreational use, either individually or in partnership, can often live with having their aircraft out of service, even if the inspection requires a longer period of time. But take an operator that has a business requiring almost constant use of their aircraft, even seasonally. In the tanker business, taking one aircraft out of service for a couple of weeks, means that aircraft can not be used on a fire. Moreover, the operator loses money.

Another example would be aircraft used for surveillance where at least one aircraft has to be in the air 8 to 10 hours a day. Or perhaps a charter/air taxi operation has a few single and twin-engined aircraft used for charter operations, they need all or most of their aircraft in the air every day. Then there are freight operations, even those using smaller aircraft. It is situations like these where progressive inspections are more suitable to meet the requirements of FAR part 43 appendix D. I wrote here that under a progressive inspection program, the aircraft is out of service for shorter periods of time, where the maintenance and inspection tasks required to be completed in a twelve month period are broken down into three or four tasks.

An aircraft owner/operator who is interested in progressive inspections starts by obtaining the maintenance and inspection procedures from the aircraft's manufacturers if they don't already have them. The manufacturer probably already has procedures spelled out for progressives and will work with the owner-operator to come up with a good progressive inspection program for their aircraft. It doesn't stop here, the FAA must sign off on the progressive inspection program.

Stay tuned for my next article, posting on January 17, where I will continue to write about what might happen in a progressive inspection program.

CAL FIRE inspection & maintenance of airtankers

In this short video from CAL FIRE TV you will learn a little how CAL FIRE maintains and inspects their air tankers (S-2Ts). CAL FIRE contracts with  Dyncorp for the maintenance and inspection of their S-2-T airtankers, OV-10 air tactical aircraft, and UH-1 helicopters, see this CAL FIRE webpage for more information on CAL FIRE's air program. All operators of aircraft used for aerial wildland firefighting have an inspection and maintenance program for their aircraft, with the specifics of those inspections varying depending on the aircraft and the operator.

According to the Federal Aviation Regulations (FAR) most aircraft, including fixed-wing aircraft, have to have certain items inspected in a given twelve month period. This list is found in CFR 14 FAR part 43, appendix D.

The FAR sets forth the manner of doing these inspections with the specifics of these inspections varying depending on category (e.g. airplane, glider, lighter than air, and rotorcraft) class (e.g. single-engine land, mutli-engine land), type (aircraft with a gross weight in excess of 12,500 lbs) and use (e.g. flight schools, charter, airlines, public-use - air tankers) of the aircraft.

It is likely that the type of inspections that are being discussed in the CAL FIRE maintenance video that I embedded here are what are known as progressive inspections. In a progressive inspection, the inspection tasks that must be completed within a 12 month period are broken down into three or four "tasks". The benefit of progressives is that the aircraft is not taken out of service for a long period of time if the inspection is done only once a year. Rather in a progressive inspection, the aircraft is out of service for shorter periods. The operator of a fleet of aircraft can stagger their progressive inspections to minimize the number of aircraft out of service at one time.

Over the next couple of articles, I will be writing a little more about progressive inspections, so stay tuned!

Aircraft maintenance and inspections are important!

In going to ground school last year and studying for the FAA private pilot exam, learning FAA regulations took a fair amount of time. The FAA regs are fairly comprehensive. And no, I'm not going to write about FAA regulations.

But it was studying the regulations that speak to aircraft maintenance and inspections that I do want to spend some time with in this blog. It did not take me all that long after I started writing about aerial wildland firefighting to appreciate the importance of aircraft maintenance and inspections. I knew that such maintenance and inspections take place on an ongoing basis, both during and outside of fire season. But I never gave any thought to the specifics aircraft maintenance and inspections.

I learned that there are specific items of preventive maintenance that private pilots can do, such as changing seatbelts; replacing landing gear tires, and replacing batteries, and replacing or cleaning spark plugs.), that these are detailed in CFR 14 FAR part 43, appendix A (c).

I learned about different kinds of aircraft inspections and who can do them, either an airframe and powerplant mechanic or an airframe and powerplant mechanic with inspection authorization, depending on the type of inspection. An inspection is not the same thing as preventive maintenance that can be performed by a private pilot.

For me, the most important thing that I have been learning and doing, is the pre-flight inspection of the Cessna 172 when I take scenic rides. The pilot and I do this together, where he is looking for things that I miss. Like everything else in aviation, this is on a check list that is kept in the aircraft. In this case, the check lists are on laminated cards for ease of use. It covers things like:

• siphoning off a little gas to check for impurities, to
• checking the oil level and the alternator belt, to
• looking at the cables in the ailerons, flaps, elevators and rudders; to
• looking at the rivets (we don't want any popped rivets); to
• checking the propeller to be sure there are no nicks.

This is just a sample of what is on the pre-flight list for the Cessna 172. It is the most important part of the flight. Doesn't matter if she just had an annual inspection the week before, you do a pre-flight anyway. Doesn't matter if you took it up yesterday, you do another pre-flight. The check list will be different perhaps, depending on the aircraft, but a pre-flight is a pre-flight.

I'll be writing more about aircraft (fixed-wing) inspections and maintenance as time goes on. In the next three articles, I will be taking about a certain type of inspection known as a progressive inspection. I had the privilege of seeing an A&P mechanic with inspection authorization perform an annual inspection on a couple of general aviation aircraft, I'll be writing about that in a few weeks. So stay tuned.

Florida - drought and wildland fire potential outlook

source: http://radar.srh.noaa.gov/fire/briefing.php (obtained on 1/8/11)

source: http://radar.srh.noaa.gov/fire/briefing.php (obtained on 1/8/11)

A while back a friend sent my a link to a Fire Weather Page (experimental) of the National Weather Service, it may be found here. So, I went there to see what information I could find about the elevated fire danger in Florida, and thought that two maps that I posted above might be of interest. In the map on the top, you can see that Florida, along with other areas in the south, is in an area where the drought is forecast to persist or intensify. In the second map, you will see that the wildland fire potential outlook for the month of January 2011, both Florida and Texas is estimated to be above normal.

The Southern Area Coordination Center (SACC) has an intelligence page with a variety of useful information, including U.S. year to date fire and acreage by state and agency that may be found here. According to the year to date figures for Jan, 7, 2011, there have been 93 wildand fires in Florida burning 1,292 acres and 6 prescribed burns at 14,272 acres. I'm not quite sure how often these figures are update, so when you go to that site, you may well find different numbers.


Another document of interest at the SACC intelligence page is the U.S. Year to Date Large Incidence List dated January 7, 2011 (again, what you see may be different), there have been three large fires in Florida year-to-date.

• New Years Fire (FL-FLS-2011-08-0848), burning 25 acres with 4 structures destroyed,
• Deep Cypress Fire (FL-FLS-2010-18-0213), burning 684 acres, and
• Black Bear Fire (FL-FLS-2011-17-0005), burning 300 acres.

All were human caused. They report start and ending dates. The three fires burned for about one day. The ending dates for the Deep Cypress and the Black Bear Fires were Jan. 6, 2011 with a start date of Jan. 5, 2011. The New Years Fire started on Jan. 1, 2011 with an ending date of Jan. 2, 2011.

My only concern in discussing these numbers is that I have no historical data to compare them with. Also, it is only one week into the New Year, so it is still early. Time will tell if Florida was a bad winter fire season or not.

Perhaps some of you will want to check out the SACC intelligence page later to see what is going in Florida.

The State of Florida has a fire information page with links to a map and a daily summary. I can not get the daily summary page to work in either of the browsers on my Mac, so I am not linking to it here. Perhaps those of you with PCs will have better luck. I can access Florida's mapping page which I can access with Firefox, but it requires you to get Microsoft's silverlight plug-in. You will want to read the instructions for their mapping system first which may be found here. They do have a link to mapping system that does not require silverlight that may be found here.

Elevated fire danger in Florida

Florida has been near and dear to ever since studied the history of the Everglades in graduate school. So, knowing that winter is fire season in Florida, I was on the lookout this morning for what is happening in Florida wildfire wise.

Bill Gabbert of wildfire today wrote here about the Three Forks Fire that was burning in Florida in late December 2010. This was a 4,000 acre that firefighters were fighting with a 9,000 acre burnout. At the time Bill posted his article, the fire was 85 percent contained.

Then I was reading the wildland fire hotlist forums, I saw this post about dry conditions in the southern part of the US, with a link to this Daytona Beach News Journal Article about drought conditions and elevated fire danger.

After reading the Daytona Beach News Journal Article, I went to the webpage of Florida's Wildland Fire and Fire Prevention Agency where I saw a report predicting increased fire danger in Florida in 2011, it may be found here.

I will try to follow what is happening in Florida and elsewhere down south in regards to wildfire activity over the coming weeks.

Added at 2:45 PM on Jan. 8, 2011. I just did a google search to try to find out happened with the fire, Three Forks Fire, that Bill Gabbert wrote about. According to this news report (with photos) , the fire was contained at 13,000 acres on Dec. 31, 2010.

Great Airtanker Video

I am feeling a little under the weather due to a winter cold, and I am finished with posting about the DC-3. I have a couple of things in the pipeline that I'm not quite ready to write about, I will probably wait until early next week before starting anything new.

In the meantime, I've embedded this video before, so this is a rerun. However, it is one of my favorites, so I hope that those of you who have seen it before will enjoy seeing it again. It is called "A Great Airtanker Video", and I believe that it s footage taken for a National Geographic piece about 15 or 20 years ago. Enjoy!

DC-3 (part 6) virtual tour courtesy of MAAM

Thanks to the folk of the Mid-Atlantic Air Museum (MAAM) in Reading PA, we have the opportunity to take a virtual tour of a restored R4D-6 (DC-3. The R4D-6 was the US Naval version of the US Army C-47 (DC-3). Both the C-47, the R4D-6 and the RAF Dakota were used as transport aircraft in World War II. For more on her history and the restoration, go here. To the best of my knowledge, the MAAM R4D-6 is airworthy as it is available for airshows.

You may also take "virtual tours" of the MAAM R4D-6, each of the following five pages of the tour has several images that you can click along with descriptions of each image:

• walk around
• cockpit
• instrument panels
• cabin
• engines

Enjoy!